If you are like most people, you will do an injection and the next day have your strength go up by 20lbs on all exercises just from placebo effect alone.
Also, don't worry about how many weeks to run a cycle. You run it until you see the gains start to slow. Then you stop. If you plan on a XX number of weeks for a cycle and then when you get to that point and stop, if you are still making decent gains you are only robbing yourself by stopping.