Depending on how bad, you may not need to reskim. Wet the thru areas with a little solvent - if they go clear, the varnish may well cover. I skimmed, then sanded thru the skim in a few spots. All worked out fine.

If you do recoat, a week or so will be fine. As soon as it's hard enough to sand without clogging the paper. At least that's the info I got from the System 3 folks, and it worked out OK for me.

Dan.