Can you use the time stone to go that far though? All I've seen them do in the MCU is make small changes, and him rewinding a book almost really complicated things.
I'm under the impression that the time stone can make fairly small time edits, though maybe its power is enhanced when its synchronized with the others in the gauntlet, but I'm not sure you can actually go back and make a change that big.
Also, don't those kind of time shennagins create a paradox? Like, if he did that, and thanos was defeated, he would have never been in the situation he was in on Titan and therefore would have never had to go back and make that change, therefor it wouldn't have happened ect ect.
I think the time gem may be the most "complicated" power of them all and harder to use willy nilly. Again, when strange was fucking with the book in his movie and just using it as he pleased things that fracture thing started to happen.