That's only the way I would to it. But I can reliably zero my bit between tool changes. I set zero in the lower left corner of my work piece, away from the sign itselft a little, then jog the bit down so it makes a hole there. Then, not matter what happens during tool changes, power outages, rabid squirrels, etc., I know I can manually re-zero. So bit changes won't be a problem.
You will, however, likely make more kindling along the way as you experiment.