I can tell you how I do it.
With the knife completely profiled, scribe the parallel edge lines, then the centerline, or spine line, on each side.
Take it slowly, making a pass or two, then switching hands and doing the same to the opposite side bevel.
Whan you get to the tip, the bevels will go past the centerline. Don't worry about that because when you do the second set of bevels, you will bring it back to center, and it is a natural way to taper the blade.
As you approach the centerline, stop, and start your next set of bevels. Be very careful at the tip so you don't get it too thin.
Stop when you approach the centerline. You want to leave a small flat on each side, before heat treat.
After HT, start grinding again, only making a pass or so on each side to SLOWLY bring the grinds to the centerline. If you don't feel you have the control to do this on the grinder, stop, and proceed by hand.
The main thing is to take it real slow, and careful.
Let us know when you get to this point, and we can go further if needed.
Edited to add: It's imperative to keep the knife horizontal with each pass across the belt, and to hold the blade the same with either hand, not letting one hand tilt etc.
