How is she doing in precalculus? How did she do in trigonometry and when did she take it?
In my experience, if a student is very strong in trig and precalculus (solid A or A+) then calculus is relatively straightforward. If a student struggles in trig and/or precalculus then calculus can be tough.
She is young to take calculus and as such I think that having a solid grasp of the material is more important than being ahead of her classmates in terms of what she is taking. Algebra and calculus are going to be important for an engineering major.