I would bring the stave to final dimensions for width( with a little extra at the tips), then start tillering, and don't do any more heat corrections until you absolutely need to, ie get it to a 4-5" brace height, but not drawn more than 15"(less if feasible). Hopefully when you get to that point, the knot will have disappeared.
I wouldn't try and pop out the knot, its likely to tear out rough.