Carson's in first, but you know, I don't see him as having much chance.
Trump has his business experience to fall back on in the next phase of the primary (the 'increased scrutiny to make sure they can do the job' phase), but Carson I don't think has the chops to sell himself as having the full knowledge base.
Heck, his being there probably helps Trump, since Trump does know how to manage better than Carson and he'll look good in comparison / more scrutiny will be aimed at Carson.
There's traditionally one or more "does well for a bit, then falls off after being put in the limeline" candidates each primary, and while Trump may shake that status, I do not believe Carson can.