It depends on the results you want, and the timeframe that you want them in.
If you have 6 weks total of Activate Extreme on hand, then I would recommend that you run that for 6 weeks. For the first 3 weeks stack it with Drive, and the last 3 weeks stack it with Primal Male.
Personally, though, I think that you need MORE than 3 weeks (at least 6-8 weeks) of each product, to get the full benefits from them.