I’m trying to make coasters with dried flowers. They float up to the top at first. The video’s show that as the resin dries (and when it has partially hardened), you then gently push the flowers back down and if you time it right, they will stay down. I’ve been working with deep pour casting resin which takes about 48 hours to dry in my nonhumid basement. How do I know what is the appropriate time to push the flowers down?