I do not think there is a certain rule in this...even different branches of the same tree have different fruit bearing sequence. There is no need to tell them apart, because once the fruit is formed, the branch point will be suppressed till next season...However if you pinch the top, a new branch will take a high priority instead of bearing fruit. In general, pinching at the 6th to 7th leave is best to increase the fruit production, in the early season. It is not recommended to do so two months before the tree goes into dormant season.
Depending on the variety, some take several years to bear fruit. Mine, a White Ischia, take almost four years..another one. the fist year, but the taste is very bland.