The fact that Doctor Strange has a plan is pretty widely accepted here, as it's less a fan theory and more just something extrapolated from the movie. I just came out for the second time and noticed some additional things to support that Doctor Strange's plan is still in motion, involves the time stone, and was not disrupted by Star-Lord. Going through here I'll be retreading commonly posted things to get to my newer observations.
Doctor Strange has seen 14,000,605 futures. He has seen 1 that results in victory over Thanos. This much is accepted, so people realize that Doctor Strange knows how to win.
Doctor Strange gives up the time stone to spare Tony Stark's life. Earlier in the movie he says that he would let Tony or Peter Parker die before he gave up the time stone. He said that before he saw the path to victory. So the assumption being that Tony being alive is essential, as is Thanos having the time stone. Though I believe that the most important thing with this was getting the time stone to Thanos without Thanos suspecting much more than Strange's humanity making him unwilling to watch Tony die.
Dr. Strange says two important and oft-quoted things to Iron Man. The first is "We're in the endgame now" indicating that everything is still going according to plan and he's done what he needs to. The other is "It was the only way", indicating that the time stone and the snap and everything that happens is the only future that leads to victory.
Doctor Strange sends his cloak to wrap Thanos' hand at one point, and he mutters to it, "Don't let him close his fist." This indicates that Doctor Strange is aware of the most minute aspects of the fight, considering Thanos closes his fist a few times during the fight without anything major happening as a result. Dr. Strange is there when Peter Quill is finding out about Gamora and freaks out, resulting in Spider-Man and Iron Man failing to take off the gauntlet. He's the only character who doesn't attempt to stop it. He also very easily could have magicked Quill away if it wasn't essential.
The last thing is the act of handing over the time stone. There's something different about this one that I double checked when I saw him holding the others. Thanos directly holds the other stones in his fingers, skin on stone. There's a green aura surrounding the time stone when he takes it and his fingers never actually touch the stone. He's holding it by the aura, and looks confused and slightly concerned when he first takes it while Doctor Strange is watching him carefully. He puts it in the gauntlet and leaves, it's at this point that Doctor Strange says they're in the endgame. I believe Doctor Strange activated something in the time stone before handing it to Thanos.
Conclusion: Doctor Strange was in control of all aspects of the fight on Titan, none of it going against his one path to victory. The heroes semi-succeeded because Doctor Strange's goal was to activate the time stone and get Thanos to take it and use it without suspecting Strange had already activated a function, and keeping Tony Stank alive. I believe that all of Thanos' uses of the gauntlet that involve the time stone will be reversible because Doctor Strange set it that way before handing it over. The key to defeating Thanos is now in his hand.
