I have been on for 33 weeks. I don't see any reason to come off. This is actually my first cycle too by the way. You grow when you are in an anabolic state, so why end it? (well you grow naturally too, but much slower)
I hate to see people on here write out their cycles and they already determine it is going to run 10-12 weeks. When week 10 or 12 comes, they end the cycle... even if the gains were still coming strong. Which is is not a very bright thing to do is you are trying to MAKE gains....thus robbing themselves of the gains that would have still appeared in the upcoming weeks. It is a yo-yo effect. You get on, you get off, you get on you get off.... sort of like standing in a room and flickering the light switch on and off very fast.