Here's my setup -- spigot with PVC pipe screwed onto it to manifold area -- water line T'ed to go to input of each manifold. Manifolds have backflow prevention built in. No drain plugs anywhere in zones.

In order to winterize (too late this year!) what I thought about doing is unscrew PVC line from spigot, attach compressor to PVC line then open each manifold one at a time to blow out zone. Is this an OK way to do it?

I understand there are specs for the type of compressor I'll need and I'm willing to buy one as I don't want to pay to have this done EVERY year.

I also read about the trick to put a rock on all sprinkler heads on the zone except for one.

Anyway, want to make sure my plan will work...