I wasn’t sure if this should go here in mechanics or in warlock, but I’ll start here.

Hello, so for these questions, I’m focused on the follow scenario:

warlock Pact of the Chain familiar: quasit /imp/sprite

Eldritch Invocation: investment of the chain master.

my understandings:

• The familiar has its own initiative and therefore its own place in the turn order.
• with the invocation, I can command the familiar to attack as my bonus action.

so this leads me with the following situations, and both assume that no hostile creature will have a turn in between us in the same round

1. the familiar moves before me
2. the familiar moves after me.

situation 2 is pretty straightforward, on my turn, I would order the familiar to attack as my bonus action and then on its turn, have it turn invisible and fly to safety (granting flight to the quasit).

situation 1 strikes me as more limited as I cannot have the familiar attack without breaking the invisibility and leaving it hanging out until it’s turn cycle around, vulnerable.

so my questions:

1) do I even have these situations correct, or is there a fundamental way the familiar acts that I am missing?

2) is there a way for me to ready my bonus action so that the familiar will strike at the start of its turn and then use its own turn to turn invisible/be safe?

and bonus question.  Could an invisible (per a spell from me) pseudodragon help at range with telepathic distractions?

The situation is the same regardless of who goes first. If the familiar goes first in the turn and you go last, then it will attack at the end of one round (on your turn in that round), and then at the start of next round when it has it's own turn it will turn invisible.

Really the difficult part is when your initiatives are separated by any enemy creatures.

You can't ready a bonus action.

Telepathy wouldn't distract any more than a creature shouting.

I think I'm reading Investment of the Chain Master differently than you... you seem to be reading it as the familiar instantly attacks during your turn when you use your bonus action. I take it to mean that you issue the order on your turn, and when the Familiars turn comes around it is now allowed to take the Attack Action. Keep in mind that Pact of the Chain has a separate feature that allows your Familiar to attack on your turn, but doing so costs the familiar its reaction.

So, unless I'm misinterpreting how it works, you do have means of accomplishing what you want...

Pact of the chain allows you to take the attack action, then forego one of your attacks and allow your familiar to attack with its reaction. So you can actually choose to hold the attack action until right before your Quasit's turn, then perform your held attack action, forego your attack to let your familiar attack with its reaction, then the familiars turn will start and it can spend its whole turn turning invisible and escaping... it just costs you, instead of a bonus action, your full action, plus yours and your familiar's reactions.

I agree with TransmorpherDDS's interpretation. For your Bonus Action you are giving the familiar the command - then on it's turn it takes the Attack action. Also - if you don't give that Bonus Action command - it can't take the Attack action (as per the general Familiar rules).

If the Investment Invocation allowed it to take the Attack action immediately it would require it to use its Reaction - just like the Pact of the Chain feature does.

Remember different things will turn different familiars visible:

Sprite: The sprite magically turns invisible until it attacks or casts a spell, or until its concentration ends (as if concentrating on a spell). Any equipment the sprite wears or carries is invisible with it.

Quasit: The quasit magically turns invisible until it attacks or uses Scare, or until its concentration ends (as if concentrating on a spell). Any equipment the quasit wears or carries is invisible with it.

Imp: The imp magically turns invisible until it attacks or until its concentration ends (as if concentrating on a spell). Any equipment the imp wears or carries is invisible with it.

The Imp invisibility seems the best as the Sprite and Quasit have extra things that make them visible... casting a spell for the Sprite... and using the Scare feature for the Quasit.

Quote from Brian_Avery >>

Remember different things will turn different familiars visible:

Sprite: The sprite magically turns invisible until it attacks or casts a spell, or until its concentration ends (as if concentrating on a spell). Any equipment the sprite wears or carries is invisible with it.

Quasit: The quasit magically turns invisible until it attacks or uses Scare, or until its concentration ends (as if concentrating on a spell). Any equipment the quasit wears or carries is invisible with it.

Imp: The imp magically turns invisible until it attacks or until its concentration ends (as if concentrating on a spell). Any equipment the imp wears or carries is invisible with it.

The Imp invisibility seems the best as the Sprite and Quasit have extra things that make them visible... casting a spell for the Sprite... and using the Scare feature for the Quasit.

 Of course, some DMs might see that the Imps description of Invisibility only accounts for its normal abilities and hasn't taken account of it being a familiar, and might impose the additional wording since it becomes relevant only while the Imp is a familiar. The same logic can be applied to a Quasit which is delivering a spell for the warlock.

Quote from Anticlonus_Antsinger >>

[Snip]

so this leads me with the following situations, and both assume that no hostile creature will have a turn in between us in the same round

1. the familiar moves before me
2. the familiar moves after me.

situation 2 is pretty straightforward, on my turn, I would order the familiar to attack as my bonus action and then on its turn, have it turn invisible and fly to safety (granting flight to the quasit).

situation 1 strikes me as more limited as I cannot have the familiar attack without breaking the invisibility and leaving it hanging out until it’s turn cycle around, vulnerable.

so my questions:

1) do I even have these situations correct, or is there a fundamental way the familiar acts that I am missing?

2) is there a way for me to ready my bonus action so that the familiar will strike at the start of its turn and then use its own turn to turn invisible/be safe?

and bonus question.  Could an invisible (per a spell from me) pseudodragon help at range with telepathic distractions?

 So first off, situation 1 is practically the opposite of the assumption in the premise. If the familiar is 1 before you, that is no different than having every creature between you in initiative.

But the situation 2, you made an incorrect assumption (not included in the premise I cut out). You command your familiar to take the attack action with your bonus action. It does not take that action until it's turn, then it can't use its action to turn invisible (because it used it to attack). This is different from the pact of the chain feature which lets the familiar use its reaction to attack.

Anyway, initiative be like that. Just hope that your familiar is as close to immediately after you as possible.

1. You did miss something, explained above.
2. No, but irrelevant (as explained above).
3. No. You have to be within 5 feet to help. You can do so without breaking invisibility though.

So it looks like Investment is not necessary to get the desired sequence of events.  I have the familiar use its reaction to attack by sacrificing my own action, then on its turn it can go invisible and be safe.

Seems then the command to attack as a bonus action just simply allows the familiar to attack on its own during its turn.  Its an overall gain of one attack in the round for our team, but no shenanigans with invisibility.  This brings up questions about haste, but one thing at a time...

Still the other benefits make the option seem attractive for a utility driven / debuffing character.

Thank you for the clarifications.

Sounds like making up rules where none exist. But each to their own.

While some may add rules, others might bend or break them more.

I've always thought you should get the magic immunity from Imps and Quasits.

Maybe some will even cherry pick the rules they like best.

Most fun for all is what i say. Enjoy the holidays.