So according to this Q&A by the Russo brothers about Avengers: Endgame, Thanos created the tech to travel through time.
So with this tech and the knowledge about the locations of the stones using Nebula's memories, why didn't Thanos just travel through time and space to those locations where he can find the stones very easily instead of going to the very specific time and place where he would be at a certain disadvantage against the Avengers with possibly all the stones.
This is the same Thanos who waited till Odin was out of picture before he made a move for the Tesseract again after using Loki failed to do it for him so we know that Thanos is a patient Titan and from the info he has Thanos should see that the Avengers with Capt. Marvel and the stones are more dangerous than Odin and Thor alone.
And we also know that the "Time GPS" that Tony made can be used to go to some other time and location as well since we see Cap and Tony do it on-screen and are also most probably used by Cap off-screen when he is returning the stones to their places.
And the genius that Thanos is, he surely must have the ability to move through time and space after reverse-engineering the "Time-gps".