Basing on the information in Lalitavistara Bodhisattva Gautama spent six years on the banks of Nairanjana river performing ascetic practices. Before this He visited brahmin hermits, was twice a student under a famous teacher, in between meditated alone in the mountains, and again went to the mountains with the Five Ascetics, etc... We have to conclude that the period before the Nairanjana river took five to six years. The cause for a later date of his leaving home is the birth of Rahula. It seems that Rahula was not the son of Siddhartha, not in a physical sense anyway. There is a tradition ( told by venerable Hsuan Hua) that Rahula was sired by pointing an ascetic's staff toward Yasodhara. Rahula was accepted by the Shakya clan and the Shakya family, who wanted an heir. Yasodhara is not mentioned in the Lalitavistara, which is Shakyamuni's own telling of His life. The facts seem that Siddhartha left home at the age of 23 or 24 (or 19), Rahula was born when Siddhartha was 29, Shakyamuni considers Gopa to be His first and primary wife, but the Shakya society made Yashodhara his wife and Rahula His son, (which is later accepted by the hinayana schools).