Sorcerer multi class help... or not. Not min/maxing.

I've got a level 2 Sorcerer I'm about to level up, 2024 / 5.5e. Again, trying to optimize, but I don't really want to dump flavor.

Cthonic Tiefling, planning to go Aberrant. Was considering Wild Magic, but that ain't my character. She's not about that. She's here for vengeance, and she's (apparently) not afraid to go face-to-face with a dragon. Admittedly a very small one, but it came up to her and she had to rely on Chill Touch instead of better, safer, distance spells. And thankfully, said dragon was shite at recharging the breath weapon, or she would have died (like most of the rest of the party.)

Plus, the psionic / telepathic elements are very on point.

So, my plan is to do a Warlock dip. Her patron would be Tisiphone, the Fury of vengeance. Fits with the Cthonic lineage, and her backstory. Primary reason to go Warlock is armor, sorcery point recharge, and probably PotB weaponry when slots run dry. Eldritch Blast isn't really the huge draw - it's undeniably great, but Sorcerous Burst is occasionally powerful, with variable damage.

My question - this seems like a good fit. But should I just stick with Sorcerer? If not, should I start the dip at level 4?

If you take it now, you delay your subclass.

If you take it next level, you delay your feat.

If you take it the level after that, you delay third-level spells.

IMO, all those are better than what a single level of warlock is going to get you. (In particular, blade pact isn't going to serve you better when spell slots run dry than your extant cantrips will.)

My question - this seems like a good fit. But should I just stick with Sorcerer? If not, should I start the dip at level 4?

To tack on to the post above.  multiclassing is a huge psychological drain on the person (not the character) as they will always be second guessing if they should or should not have dipped that last level increase.  When you are playing session to session, it can be a bit of grind as you debate and execute your previous choice to multiclass.

If you start out as a higher level PC, multiclass is not bad.  But starting 1st level and slowly week in and week out playing, multiclassing is not such a great choice.