Clomid days 3-7 or 5-9

Eymy

Does anyone know the difference between both. I've seen some people that are doing it 3-7 and other 5-9. I have done 3 cycles of clomid days 3-7 now with no luck. I feel my af coming up it should be here tomorrow. I was wondering if I should switch it up to days 5-9. Any suggestions????