Non trads & post baccs- How many credit hours do you take while balancing a full time job?

I (24F) am kind of cheating because I’m pre MPH (trying to show some upward trajectory before I apply) but I asked on a couple different forums and thought it was a bit dry. I’m also hoping the information in this thread can help others. Non trads and post baccs who work full time: how do you manage coursework while working? How many credit hours at FTE is too many? I work full time as a public health microbiologist and am planning on taking a graduate biochem course and a 400 level pathophysiology course (totaling 6 credits) this semester. Is it any different than being an undergrad working part time and taking a full course load? Thank you in advance!