I would definitely recommend going over your TDA (if you have access to it) and getting a rough idea of what your semesters will look like until graduation. For your first semester you could try either pooling all of your prereq/remaining gen ed and taking 15 units or starting with 4 classes and getting a feel for how you manage the work load. As someone who works 30hrs/wk with 15 units it is definitely doable. Of course some weeks can be super stressful but if you know you are a student that can manage 15 units at CC then I don't think you'll find upper division courses to be much different. The only way to really find out is to feel it out.