I took nursing pre-req classes my freshman year many years ago and did terrible (D+ to C range) in them. I talked to the nursing advisor at the university and she said that because they were several years old they wouldn't even count those grades towards the prereqs. (I did have to retake them, however). In fact, her exact words were, "We can count those classes, dear, but I don't think you want us to." She was right
I bet your pre-reqs are weighed alot heavier than total GPA. I don't think it would do any harm to talk to your advisor first, though. If nothing else, it shows you are proactive--a very good trait for a nurse.
BTW, my grades are great now--I just was VERY ill-prepared for the classes I took that first year. Ah, if I'd only known then. . .