>> Identify a part of this system that can work somewhat in isolation and is non-critical if at all possible.
I'm probably thinking about this at a different level, but when I start something new I like to find the core pieces and the most difficult pieces and see if I can tackle those first. Everything else builds on top of that. I'm assuming you mean to start at a higher level piece that will need to use all of the lower level pieces. That's good too because it may help identify what those difficult core pieces even are that I'd like to go after first.
It’s a new team. This non-critical part is your shakeout cruise before heading off into the open ocean. You can identify how well you hired as well as how well you prepared for these contractors to begin work. Make appropriate calibrations or worst case scrap it and let the whole team go.
If they produce some big mess you will find out much quicker than if you set them loose on the big project. Small deliverables which incrementally get larger is how you roll on a new team. It allows you to get fast feedback and make small calibrations as you go. Hopefully avoiding the “fire them all” failed project scenario
I'm probably thinking about this at a different level, but when I start something new I like to find the core pieces and the most difficult pieces and see if I can tackle those first. Everything else builds on top of that. I'm assuming you mean to start at a higher level piece that will need to use all of the lower level pieces. That's good too because it may help identify what those difficult core pieces even are that I'd like to go after first.