One thing you can do is keep an eye on the exact color at which your steel goes non-magnetic.
Do this in a dark area so you can really become accustomed to that color.
Over time, you become so familiar with that color that you can nearly identify it without a magnet. But always check.
Now, keep heating your steel and watch that color brighten up to the NEXT!! color range.
Rather than a sort of bright red, it will change to a orange-ish color. You can watch that color creep up from the thinner sections of the knife into the thicker sections.
This is where things get tricky.
If you want more of the thinker portions of the knife that orange color, you risk getting the thin portions too hot.
That's bad.
That's when you need a more controlled forge so that the thin areas are not over-heated.
Keep at it and let us know of your successes.