But unfortunately for him and the GOP, I don't think the candidates will leave early. Rubio, Kasich, and Carson stayed long past their expiration in 2016. It may have not really mattered then as Trump had a pretty solid polling lead regardless, but it probably would have been more competitive.
With how condensed the primary is too, there really isn't much margin for error. The candidates pretty much need to bow out before the primaries, or at least before Super Tuesday. There are too many winner take all contests at stake in the GOP primary that a crowded field is particularly costly for the underdog.
(not that I would find DeSantis any better than Trump)