About 30mins. for me. That is enough time for the methylene chloride to evaporate. I don't leave uncovered for a long time, it will pick up dust from the air. It will be like "fly tape" sticky.
I also let it sit for about 20-30 min before doing anything with it. I sprayed JIG on a stock crap wheel out of a BSA kit and it straight up melts the wheel and pretty quickly too!
I'm at about 15-20 minutes dry time. Don't forget to shake off the excess before allowing to dry. No issues thus far with this dry time. Use the time you are best comfortable with.