I'm new to Leatherworker.net, so, hello....
This will probably make a few of you laugh, but with the few holsters that I have made, I found that setting the holster on top of a lampshade of a lit lamp for several hours after I finish wet molding them does a pretty decent job of drying them out and stiffening up the leather.
Funny thing, I also found out that water that is too hot(boiling) will shrink leather instantly and make it as hard as a rawhide chew toy for your dog.
I leave the pistol in the holster inside the wet holster for about half or a little more of the time on top of the lampshade then remove it for the final drying.