Basically, leaving your cooling system dry and letting it sit will cause you no issues. Don't run the vehicle (obviously) without coolant. If you run it too long, this can cause issues.
If you have an aluminum block, there's no chance for corrosion. The aluminum will have already formed a protective barrier, which inhibits corrosion. If an iron block, you'd have to let it sit for years in the open air (outside of a building) for it to corrode enough to cause any issues. Seeing as how the cooling system is inside the engine, there's no real chance for it to corrode. Any coolant which remains in the system will also help prevent any corrosion.
Really, there's no real reason to fear leaving your cooling system dry (or mostly dry) for a few weeks, or even a month or so. You'll most likely have it all back together well before any damage would occur.