No. The person cannot perform tayammum unless the time for prayers sets in. But if he has performed tayammum for some 53 obligatory or recommended act and his excuse (on account of which his religious obligation is tayammum) continues till the time for prayers sets in, he can offer his prayers with that tayammum. However, if he knows that his excuse will cease to exist by the end of the time of prayers, he should wait and offer prayers with ablutions or bath, as the case may be.   _{Your Comment}