Boot leather and holster leather are 2 different things though. My boots don't need to have retention, my holster does. People do all sorts of crazy things to a baseball mitt that I would never do to a holster.my grand pa used to strech new boots by filling them with water and puten em in the freezer overnite.after they thawed out he would pour the water out,and wear em till they wer dry.he said they fit like a glove and felt like he was wearing socks.but grand pa was 82 and did a lot of strange things.
It's probably better now than it was in '75.1975 Rawlings XPG 26 Willie Stargell glove. Still going.
I would NOT use any oils that would soften the leather. Leather holsters need to be rather ridged and retain their shape to stay out of the trigger guard.
Remember this guy:
That's my method also. I wrap it with a piece folded over twice and force the gun in. I let it sit overnight then double the waxed paper the next night. After that it's a perfect fit. (You will probably have to have the paper long enough to slip over the muzzle so it doesn't slide when you try to cram it into the holster. I usually have to place the gun and holster muzzle up and lay the back of the slide on a wooden table and really push.)I have never used the sock method, but wrapped the gun several times with wax paper before inserting it into the holster.