...just found out my car is at the prep ctr.....what goes on here and how long

does it take before it's put on a car carrier?

your car will be checked thoroughly in VPC. It will be reprogrammed and fitted with US regulation.

In about 3-4 days, your car will be sent out to your dealer. expect 1 week from now, your car will probably arrive on your dealer (but it depends on where you live though).