Reddit reviews The Encyclopedia of Candlemaking Techniques: A Step-by-Step Visual Guide

Oh, I'm sorry to hear it mushroomed at the bottom! That's never happened to me. I can tell you the method I use exactly and maybe that will help.

I generally let the candle cure for at least a full day (sometimes longer) before spinning the bottoms. I cut the wick very close to the base, and create a small burrow to tuck the wick further into the candle. I also will put the heat up a little higher if need be, and work quickly. It generally shouldn't take longer than 60 seconds (if that). I apply even but gentle pressure from the top center of the candle and move it in a swirly pattern rather quickly, then quickly swipe the bottom of the candle on a piece of absorbent paper (brown paper grocery bags work great for this- just don't do it across the inked parts on the outside of the bags or you'll pick up the ink on your candle bottom).

Maybe try letting the candle cure longer and putting the heat up a little higher on your skillet, so you will be able to flash melt the bottom quickly, without heating up the rest of the candle. Also if you can't get it even after the first 30-60 seconds, pull it off the heat and let it cool down for a while, before putting it back on the heat. That should prevent the heat from reaching past the very bottom of the candle.

I would also consider picking up some books on candle making. Youtube videos are good sometimes, but no one seems to want to give away trade secrets with candle making online, since we tend to spend a lot of money and time perfecting our craft. The books are great for beginners, they really spell out the steps from start to finish for each kind of candle you could think of. I recommend this one
https://www.amazon.com/gp/product/0762406011/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Nature's garden has some pretty good tutorials too that are worth looking over https://www.naturesgardencandles.com/freecandle/candle-classes

Best of luck to you!