If Clomid is going to work for you, it is likely to do so within 3 cycles. The statistics are 80% in 3 cycles. BUT, that is for the women it works for. There are exceptions to every rule, I hate to say. There % is much lower for conception cycles 4-6. Some will still conceive during that timeframe, but much fewer.
Clomid is a pretty standard starting point and has been around forever. It used to be the only med out there and was just called "The Fertility Pill".