Adding objects to resin jewelry…

Hello,

I’m planning to do a resin project with my jewelry students. I have read and researched quite a bit. I also checked out a few books with step-by-step projects for ideas. One of the things I am finding conflicting information on is when to add your object(s) to say a bracelet mold. Is this immediately, 15-30 minutes after you’ve poured your resin, or in some cases I’ve read 3-5 hours later. Does this depend on the brand of Resin? I’m looking at Craft Resin Epoxy Resin and Artresin. Ideally I’d like for them to be able to add to their asap as the class is an hour. Please clear this up for me!