When is the right time to contact my choice of the B3? Multiple Degrees?

[sanantone]

Regardless of your student standing, very few universities will give a 90 credit block transfer for a second degree student. Most places will just accept credits on a course-by-course basis and perhaps waive gen eds.

I would skip the Social Science degree and go for a BSBA. You said that the BSBA was for your career, so why not get an MA in whatever Social Science discipline(s) interests you after the BSBA? Interdisciplinary MAs are more numerous, generally cheaper and less contingent on your personal/career situation than MBA programs. Not to mention that if it's just for personal reasons, you have a lot more choice in terms of individual program/institution and mode of study, whereas MBA programs require more careful selection. There are very few online (max 4-5 in the US) or part-time MBAs which would be able to even remotely reliably facilitate career-switching, and even then it is almost universally discouraged by business schools and recruiters.

I'm going to have to disagree. There are hundreds of MBA programs out there, but not many online interdisciplinary or liberal arts masters. When you can find them, there is a good chance they either don't offer what you want or that they'll force you to take a bunch of credits you don't want. For example, if someone wants to fill the masters with psychology and sociology credits, there aren't that many programs that will either let you do that or offer enough of those two to fill the whole degree. One of the more flexible programs out there is WNMU's MA in Interdisciplinary Studies. They don't offer a sociology concentration. The closest thing they have is social work, and only 9 credits are offered in that subject. A lot of the other liberal studies programs will make you take 6-10 credits in junk courses. Fort Hays State University is a good example.
https://www.fhsu.edu/mls/conc/conc-politicalscience/

Online MAs in social science are extremely rare. There are several online, AACSB-accredited MBAs that are less than $20,000. Honestly, an MA in social science is overkill for social service jobs that only require a bachelors and worthless for jobs that require a masters because these jobs tend to require licensure. The only thing it might be useful for is teaching as an adjunct if one can manage to get 18 credits in a subject. If someone has experience in business, the MBA would actually have some worth. For someone who has no experience, a bachelors in business isn't really that much better than a BA in Social Science. Business administration majors are the most underemployed. There are way too many people with bachelors degrees in business administration, and it continues to be the #1 major in the U.S.