It is marked wrong, but I thought “previously” was 先に… and before is simply 前… I am very confused now. I thought 以前 was more in context of “before X” as in “compared to here or now, before is X…”, but am I wrong in assuming this?
For the record, 以後 has as primary meaning “after this” and only “after” as secondary meaning which makes me even more confused.
As I understand it, I think “before this” is synonymous with “previously”. So it would be: I did a thing 以前 (before this/previously), and I’m doing a thing 以後 (after this). I’m pretty sure the concept is the same for both words.