That's a terrible idea. You're overcomplicating the plot.

Also, the scene with Tony is maybe not even the begining of the movie. It's more likely Rocket and Thor will search for Star Lord and the others, and find them in the last moments. Captain Marvel has nothing to do with this.

A multiverse is possible to come out of this movie, but not in a way you suggest. Your idea has too many plot holes if we go by the information we already have. Just the premise is a plothole. If our Tony is not "the one" then there was no reason for Strange to sacrifice the stone, since the other Strange has to do it. Even if there is a reason, they'd have to explain that, and in a movie format it gets too complicated. For the viewer the plot has to develop organically, without giving us a twist at the begining confusing 50% of viewers for the rest of the movie.