So Doctor Strange was full of BS

Dude, you're not thinking straight. HOW is Strange going to kill Gamora? So he reverses time to when she was still alive. Great. What next?
1. He doesn't know where Gamora is.
2. He doesn't even know who Gamora is.
3. Even if he knew, how does he get to Gamora? We don't know how far his portals can travel.
4. Even if he did get to travel to Gamora, Thanos is already there. How does he get past Thanos? 
5. We also don't know just how far back the time gem can reverse time. So far we've only seen it reverse a few minutes. We don't know if it can go all the way back to before Gamora was taken.