Don't tap too heavily when going from the neck side to the headstock side. Multiple light taps only. I was getting a friend to do this on his Strat kit neck so we could fit a bone nut. I said 'gentle taps only' but each tap got heavier and then a piece of the curved wood in front of the nut shot off across the room. Luckily it was one piece and I glued it back in for him, but you don't want to do that if at all possible. So light taps from the sides, then heavier ones from each end. light taps form the sides, heavier ones from the end. Repeat as necessary until the nut starts moving, then only tap from an end.