i have a mess of experience with tincture, both glycerin and alcohol, both ambient temperature and agitated with heat........

decarboxylation is very important if you're never going to expose the tincture to heat. i use a sheet of foil in the oven at 220 degrees for about 5 minutes. when i say tincture to heat, i mean like when i add tincture to a 310 degree sugar base. 310 degrees of sugar will decarboxylate the carboxyl group from the molecule and activate the thc.

freezing of the plant matter helps make the trichomes brittle and more easy to remove as well as drying out the plant through sublimation. i don't think it does much else.

tinctures made with alcohol, imo, have turned out more potent and easier to use than the glycerin, but the glycerin is far easier to consume, tastier.
i make glycerin tinctures in the crock pot switching between low and high, off and high for an entire day. after a day, it's ready to enjoy.

alcohol tincture, or green dragon, is a little more complicated. i use heat and am finished in about an hour from start. i'll put some ground plant matter in a mason jar and cover it with grain alcohol (the large proof stuff). with ventilation raging, i put the weed/alcohol jar into a half pot of soft boiling water. alcohol boils cooler than water; a soft water boil should make a raging alcohol boil. stirring nearly constantly, i mix until the alcohol volume has decreased by approximately 50%,at which point i run the mix through a set of screens and allow it to cool.

figuring out dosage is fun.......

in short, though, yes. i think you can heat your medium and decarboxylate the plant matter at any point. your biggest concern heating alcohol to x degrees should be blowing up your house........