The MAZE procedure corrects atrial fibrillation; many patients require no further treatment and restores a regular, coordinated heartbeat
The risk of this procedure is felt to be low in general, but the risk will be affected by each individual's specific health conditions (heart function, lung function, kidney function, etc.). In addition, some patients require a permanent pacemaker postoperatively. This is thought to be due to underlying disease of the SA node.
I don't know the answer to your the question. There is a possibility the heart rate will not be normal and that would indicate an SA dysfunction. Under that circumstance, there is no acceptable reason to wait.
The risk to wait is a slower than normal heart rate, and that risk is a probability of blood clotting, syncope (fainting), etc.
It really requires a professional evaluation to weigh the risk with the benefits, and to take into consideration your mother's general health, etc.