To start,make sure all surfaces are clean.I like to sand the insert and roll a small piece of sandpaper and twist that inside the broadhead ferrule.It doesn't hurt to also clean surfaces with acetone or alcohol.
Keep the leftover mixed epoxy and when it is hard enough that it can't shift,unscrew your broadhead and retighten.It just has to be firm enough that when you unscrew,it won't move the bond between broadhead and adapter.You are just checking to make sure it will unscrew.I can't remember set times on JB but probably 3 hrs or more.Check your mixing pad.You will have quite a long window where you can still unscrew the broadhead,even if a little epoxy has drifted between insert and adapter.Once you break that seal,it will stay that way.
Again,if you are worried about it,wax the insert.You will have no sticking problems.