Most HVACs have a time delay module in them from the factory these days but they are a delay after power off deal. If the power was off for X minutes it starts immediately.
For the OP's problem you want "delay on" relays set to different times for each compressor.
Five to Ten seconds between starts should do the trick without being that noticeable to the users.
http://www.grainger.com/category/time-delay-relays/relays/electrical/ecatalog/N-8erZ1z0move
