When and how much should I pay my builder?
If there are subcontractors involved then get lien releases from them before you pay the GC for the subsequent stages. As in, once the foundation's done and they've started on framing don't pay more until you see a release from the foundation sub. This way you know the GC is paying them, not stringing them along. This happens, the GC pockets the money, disappears and then the subs come and file liens against YOU for the work that was done. They deserve to be paid, of course, but you have to make sure the GC is actually doing it.