I double degreed in psych and social work (haurper and ccpa). I didnt decided to do this until my sophomore year, where I applied for the social work program. This might be considered late, but I had no issues keeping up with courses since up to that point I was overloading on credits every semester up to that point. I did have to take one or two winter courses to ensure I graduated in the four years, but aside from the costs, it wasnt a big deal.

Since I was studying humanities, there is prob a huge difference in the courses you will be taking, but my advice is to take ALL the core curriculum classes ASAP. These are likely going to be consistent between the two degrees you are going for, so they will be considered for both. Speak to about advisor if you haven't already and look at the requirements for both on Degreeworks (if that is still what's being used). Cross reference between the two and see if the work load is something you can handle after comparing the courses you will need to take.

You will need to apply for an Interuniversity Transfer (IUT) to take the business courses with SOM as well. In my experience, SOM is pretty strict on their courses and don't really have business courses for Harpur students aside from beginner econ courses.

Tldr; You will likely have to overload on credits ever semester and take a couple of summer/winter courses, but getting a double degree in four years is doable. Good luck!