Is their any Age limit to become a Buddha?
There is no such age or age limit. For example,  Kassapa Buddha, the sixth of the Seven Buddhas of Antiquity, and the third of the five Buddhas of the present kalpa practiced austerities for only seven days. Kassapa Budda attained Parinibbhana at the age of forty thousand years. At that time children would get married at the age of 500 according to legend.