This is a good idea because you could also get in good with whatever body shop and you could probably get a bunch of their left over paints on top of it!
Warm up your spray can in a pot of warm water and then take it outside to spray it quickly. Otherwise, like others said, pre-paint your winter projects.
I got the convertible top done today. I used a sandwich baggie for the rear window to add realism to it (a trick I picked up from another member here).