If your mold is hot enough, just let the hook sit inthe mold for 10 seconds before you do the next pour. If I am having that issue, I put the hook in, close it, then cut the sprue off the one I just poured. That gives the hook enoug time to heat up. I do this with up to 8/0 saltwater hooks, and I never need to do other than that. My work area is in the garage, and the hooks do get cold.
I do have 2 molds that I have to tilt to pour better, and my Shad head mold, if it gets TO hot, it doesn't pour as well around the collar.