Going out solo - how to smoothly transition clients?

Hey folks,

Hoping for some insight from those who have started their own shops. I am the number two guy at 5-10 person firm (only one holding any commissions besides the owner), looking to go off on my own at some point in the next year or so if I can't get a better deal financially in my current role. There's other frustrations/reasons as well, but not the point of this post.

I feel I've got a pretty good handle on the business side, in my current position I'll quote projects, run them start to finish and then assess the margins after the fact. I know all of the expenses, and I have a pretty good idea of what the owner takes home every year.

One of my main concerns right now for planning is this: many of our big repeat clients were brought in by me, and deal directly with me on all of their work. The owner hasn't even met most of them. I aim to be able to "bring them with me" since I have no formal work contract, non-compete, etc. that would prevent anything of the sort. However, there's almost always work on the go with these clients, so how do I go about cutting ties with my current firm without leaving these clients stranded halfway through ongoing projects? Do I just try to time my exit in a way that minimizes impact to these clients?

Thanks for any insights!