Maybe I'm misinterpreting the movie, but I don't think this is correct at all. If you cut out the first and last 10 minutes of the movie, then maybe you could get the impression that it flows somewhat like this.
I might have misunderstood though.
One thing that strikes me as off, however, is Cobb's length of time spent in Limbo. It's only slightly shorter than Saito's yet as far as the audience sees, Cobb only spends a brief amount of time there to find Saito, as evidenced by his relative lack of aging.
one explanation i've found online is that since Cobb's mind is more aware of limbo, it's better able to handle the time he spends there, so he doesn't age nearly as much as Saito