So here’s the thing, querying authors. Number 1, if you’re still messing with the manuscript, wait until you’re NOT doing that before you query. Querying is for manuscripts you think are as ready as you can make them.
Number 2, notice I said “as ready as you can make them.” Keep in mind that many agents are hands-on with manuscripts they’re considering, and they will likely suggest changes if they’re interested in representing your idea. You can incorporate any small changes you’ve made at that time if you find yourself there. Small changes are not going to be what tips a rejection over into an acceptance.
And if you’re still making big changes at this stage . . . see #1.
The exception might be if you’ve gotten some intense feedback from a professional and your work has changed significantly as a result, AND an agent currently considering your work has a long response time. If you get to the point where you need to nudge the agent and ask if they’re still considering your work, you may also want to mention that they may want to review the latest copy if they’re still interested.
What you want to avoid is pestering agents with “the latest,” because truly, they don’t care. You need to learn how to put a project down and stop messing with it. I understand that feeling very well, seeing things you want to change, but at some point it’s finished and you have to be content with that.
Be patient and wait until you’re ready to keep your hands off it for a while before you start querying. Your job is to write a book, and you shouldn’t interact with agents to ask for their representation if you’re still treating your book like an active draft.