Re: Building a rifle...would this work?
If your buying a "boutique" action then it should be as simple as fitting a barrel.
No further action work should be needed. I've spoken with Jerry Stiller on a number of occasions now. I'd have a difficult time accepting any of his products requiring additional work to "true up."
As for your build and your question:
There's certainly nothing wrong with having your barreled action fitted before your able/ready to move onto the stock work. I do think though that if funds are the delaying factor it'd be better to wait and gather your parts inventory first and then "shot gun" them to your chosen smith for fitting and assembly.
The reason is (from a smith perspective) I'd much rather have all the stuff in front of me rather than ship things back and forth. With all of it in front of me I can "take it in" so to speak and ensure the parts are compatable before moving forward.
- Experience has taught me that a customer's best intentions can sometimes lead to problems. Things like big barrels in skinny stocks, magazines not long enough for cartridges, wrong twist rates for the intended bullet weight class, an action with the wrong magazine mortise, etc.
All of these things have happened at different times over the years. Just be sure your components are compatible is what I'm trying to say.
As far as the operations with a build:
It's a very difficult question to answer as they can vary quite a bit depending on application, budget, and expectation.
What I can say is your first step in this is finding someone you can do business with.
Key factors:
Trust
Communication
Experience level
Business ethics
Professional reputation
If any of these lack, move on as there are too many good gun plumbers out there.