So, I'm looking to get some feedback on the game-balance aspects of multi-classing.  I'm currently working towards a Way of the Shadow monk, and I like and am excited to get all the goodies for the subclass.  But, I'm toying with the idea of adding some rogue levels mostly for the hide and the movement bonus actions.  To do so, though, I would delay monk levels and the abilities unlocked, and I would delay the stat/feat bonus levels.  In general, do folks find the "penalty" of these delays is sufficiently offset by the benefits of multi-classing?  Is a 4/1 monk/rogue as effective as a 5 monk?

Timing wise, what is the best point to multi-class?  I'm sure it largely depends on the classes in question, but any general principles?  And how many secondary levels should one take?  I'm most interested in the L2 rogue stuff, and don't particularly care to subclass the rogue, but and considering taking up to 4 rogue levels mostly to stay on schedule for the stat/feat bonuses.  

Whether to multi-class or not very much depends on the combination of classes you are planning to use.  Some synergize nicely, some don't.  Thematically a shadow monk works well with rogue, and both are dex based classes, but there are downsides as well. Sneak attack requires a finesse or a ranged weapon and unarmed strikes function similarly to finesse weapons, but are not by RAW. Monks are one of the classes that most benefits from sticking with it, so I wouldn't recommend 4 levels of rogue.  One level of rogue is nice for expertise and sneak attack, but is best taken at first level to get the extra skills and weapons. Cunning action at second level is nice for the hiding as bonus action, but as a monk you can already dash and disengage for 1 ki point. If it's too late to take a rogue level at first level, then I would wait until you get extra attack at monk 5.

I would go multiclass after you reached lvl 5 monk the extra attack you get will greatly increase your damage output.

Quote from Unruly_Cow >>

Whether to multi-class or not very much depends on the combination of classes you are planning to use.  Some synergize nicely, some don't.  Thematically a shadow monk works well with rogue, and both are dex based classes, but there are downsides as well. Sneak attack requires a finesse or a ranged weapon and unarmed strikes function similarly to finesse weapons, but are not by RAW. Monks are one of the classes that most benefits from sticking with it, so I wouldn't recommend 4 levels of rogue.  One level of rogue is nice for expertise and sneak attack, but is best taken at first level to get the extra skills and weapons. Cunning action at second level is nice for the hiding as bonus action, but as a monk you can already dash and disengage for 1 ki point. If it's too late to take a rogue level at first level, then I would wait until you get extra attack at monk 5.

 But then level 6 gets me Shadow Step . . .

I'm also pretty happy with my stats.  I have 17 Dex and Wis out of the box, so I will certainly take the L4 boost to get each to 18.  After that I think I might focus more on feats.  Thinking seriously about Mobile, which I suspect would further reduce the ooomph of some of those rogue goodies.   I will say that I am not hating how Raelis plays (although he's currently only L2), and it may be that as I level him I won't really feel like there is anything "missing."  That's more the way I'm leaning now any way.

I've also talked some of this over with my DM and he's not completely opposed to a respec.  I will contemplate doing that for the L1 rogue first.  I might also ask him for a house ruling on unarmed monk attacks as finesse, particularly with the caveat that I won't return for more rogue levels.  1d6 doesn't seem like it would break anything, especially at intermediate to higher levels.  

As a Monk your movement speeds end up being ridiculous. You’ll be able to go almost everywhere in combat. Mobile looks nice, but your movement ends up being so high that it doesn’t add enough to justify it to me. I’d increase your dexterity and wisdom to 20 instead for the max AC, max bonus to hit, and max saving throw when you use your monk spell like abilities. 

Quote from Tim>>

As a Monk your movement speeds end up being ridiculous. You’ll be able to go almost everywhere in combat. Mobile looks nice, but your movement ends up being so high that it doesn’t add enough to justify it to me.

You don't take Mobile for the speed, you take it for the free pseudo-Disengage and ignoring difficult terrain when you dash. The speed bonus is just the icing on the cake.