Is the arrival of the time a condition for tayammum, and is tayammum a dispensation?

Question : May Allah reward you. Is the arrival of the time a condition for tayammum?

Answer : No, it is not a condition. The only condition for tayammum is the absence of water or the harm caused by using it. As for the arrival of the time, it is not a condition. So if you know that you do not have water, you may perform tayammum before the time enters and pray when the time enters. However, if you expect to find water, do not perform tayammum until the time enters. It is both a dispensation and the default ruling. Lowering a person from using water to using earth is a dispensation, and since it is necessary for one to perform tayammum for the prayer, it is the default ruling.