I am a home owner & have just replaced the sloped ramp to our storage shed with 1/2" PT 2 weeks ago. We live in the Atlanta, GA area so temps have been 90s for highs, with showers frequently. 1) How long do I wait to paint ramp? & 2) do I prime before painting?
The rule is - flick water on the dry plywood. If it beads, wait. If it absorbs, you're ready.
Always prime first. NOT Paint & Primer-in-one hokey. That's not actually primer, it's just thick paint. Use a good quality acrylic wood primer rated for exterior, or better yet, use oil based Kilz.
Editting to add: I regularly cheat a paint job on green pt, using only acrylic latex primers amd paint. However, expect to have to repaint after one year.