I didn't use GM but I did use CM and just set mine outside (was around 5C, don't know what your temps are), they didn't gel and it worked great. Others suggested to me that if I wanted to put in the freezer to put plastic wrap over the ends and secure it tight before laying it down but if the soap is still liquid it might spill or if the mold isn't full the liquid can shift, giving you weird shaped bars. Best to wait until it's firm before laying it down.
My GM soap gelled in my Willow Way PVC tube mold all by it's onesies It's a lovely soap, though! I had some extra batter, so I put three in my Crafter's Choice round molds and the difference is obvious. Ignore the ash