Keep your weight on your heels are are directly under where the tibia connects to the foot. Keeping that weight on the heels IS NOT a bad habit. Letting it shift forward to the ball of the foot is, especially that over exaggerated heel raise in your warmup drill.
I dunno. I don't think you want to be where the toes of the foot are coming off the ground but come close to that.
Coming from a traditional American baseball atmosphere I want to just say "Stay on your fucking heels!" I don't cuss when I coach (well almost never) but it's what I would say and tell myself. Stay on fucking heels. Stay on fucking heels. Stay on fucking heels goddamit.