Here's my views, for what there worth. Heat treathing early, why do it when your taking away the wood your treating. Heat treating dos'nt treat the whole bow it only go's 1/8 th to 3 /16's deep. Your suppose to finish your tillering. And it you do your toasting evenly your tiller won't change. Your bow weight will pick up at least TEMP.
HEATING CHANGES THE WOOD CELL STRUTURE. Here's something else to think about. With you toast the belly your dehydrating the belly again also changing the woods cells structure. Dehydrating the belly, changing the cell structures also makes woods like hickory has belly compression. way less then it could be.
Personally any heating isn't good for any wood IN THE LONG RUN. Woods like hickory toasting the belly will temp. make your bow pick up a few pounds. I promass you in a year or 3 and as most of you know that answer, String follow down the line.
I've build at least 30 hickory bows. Lots of heat heating when I startedbuilding bow the first few years. Why because you were suppose to ,you learned to do this way. Dos'nt mean it's the right way to do it. EVEN IF IT'S NOT A SOUND THING TO DO PEOPLE STILL DO IT.
Any unheated bow out last a heat bow. I've had unheated bows reach 10, 12,15 years. A lot you'll never see a bow that's use'd that's been heated reach that old.
Remember heat those bows because that's the way your surppose to do it.
Plus if you heat treat if to quicky to hot your diffentely looking at excessive string follow.