Simplest advice: Structure your schedule so that you can devote one semester each to the proof-based courses: Abstract/Modern Algebra and Real Analysis.

My Story:

I earned a BS in mathematics (and BA in Philosophy/History) as a working adult (late twenties – early thirties, tech support and later developer) with a 1.5 hour commute between work and school.

I didn't have any significant difficulty until Real Analysis. That's usually the "weed-out" course for math majors and for which absolutely none of my programming experience prepared me[1]. I ended up switching to Philosophy/History for a while but luckily got the confidence to try Real Analysis again before completely giving up on the math degree.

I think anyone with an aptitude for programming will be fine in the math courses that are science and engineering-oriented. However, real math is about reading and doing proofs; if you have not done much of that I would try to arrange the schedule so that you end up studying stuff like Real Analysis and Abstract/Modern Algebra exclusively in a semester.

[1] In fact, my programming experience probably hurt me because I was overly focused on the “fine logic” aspect of proof writing rather than trying to understand the big picture.