A lot of undergraduate differential geometry doesn't require much more than strong multivariable calc and linear algebra, and some mathematical maturity. Generally, it will be something like a "differential geometry of curves and surfaces" course taught from books like Do Carmo, O'Neill, etc. These books develop DG from a much more concrete, intuitive cases, and them abstracting them from there. They do build up some topological machinery, but never really to the full abstraction that's needed in a full course on topology. They usually just explain such concepts just enough to be applied to the course. For higher level DG, you need to be well acquainted with the language of smooth manifolds and such, which does require a bit more topological background.
The best thing to do would be to find out the book you're using, and see if you can get a syllabus from past classes. I actually found it useful to have learned DG from O'Neill before learning things like smooth manifold theory and more advanced diff geometry, because it provided motivation and examples of concepts I hadn't seen yet in full rigor.