Do not heat bend after glue up. Glue doesnt like that. No need to heat bend at all actually if you like BowAholic shows and glue the backing to the core while inducing deflex and reflex during glue up. Add a handle piece afterwards. The core wood needs to be 1/2" or less in order to make those bends. 1/2" of wood, with a 1/8" or less backing can make a 70 lb bow.
Pretapering the core from 1/2" at the center to 3/8 at the tips helps the core to take on a more even reflex during glue up and expedites the tillering process better than if the core is a consistent 1/2 thick from end to end, but it's not absolutely necessary.
It can be done other ways. It's just not as straightforward and accurate. For instance, early on, I flattened the backs of full staves, reduced their thickness enough to bend them while gluing on a backing. What a pain in the butt it was, but it worked... kinda.