There was a series called Sweet Valley University (maybe having had SVH beforehand helped). Freshman year I'm sure would still be interesting (remember, kids like to read about protagonists either their age or a bit older)
Yes, but that was a spin off of a hugely successful series - and prepackaged.
And there are select other books in YA dealing with the first year of college - but they are few and far between, tend to be either from already successful authors or have been published abroad first, or deal not so much with college, as with that first 6 months after high school.
So...as a debut, I won't say it is impossible to sell a debut with the MC in the first year of college - but it's harder than if the MC is in high school or in that summer between high school and college.
Now, I think that we may begin seeing more first year of college stories - and they do seem a little more common in books with lgbt content.
But, at least for now, the first year of college setting makes it a much, much harder sell as YA.
So...what that means IMO is that the writer needs to be sure that the college setting is essential to the story - ie, that the story can't work just as well in a summer program, summer before college, or boarding school setting. And if the writer decides it must be college, then just know it may be a harder sell as a debut novel.
~suki