Not prohormone--steroid.
No, I would not do that. Rather, select the oral that best fits your goals and use that the entire 8 weeks.
For example, if your goal is size & strength, you you would be way better off using SD the entire way through, rather than using SD for 2 weeks, then Epistane for 2 weeks, then Halo Extreme for 2 weeks (not related to Halotestin, but more like T-bol), then LMG for 2 weeks.
Your gains would only be a fraction as impressive when using those 4 drugs compared to a single extended run with SD. I am not trying to say that switching AAS does not have benefits, as I believe it does, but it depends on the circumstances.