I would expect visible wear to show within a few months. Rounds tend to groove the frets quickly. While this may not require immediate attention, it is noticeable.
I've only had one bass, a 62 AV Jazz, that has required any attention to the frets as a result of using roundwounds. The bass is an 83 Fullerton and about 3 years ago I had fret work done, mostly because it had the dreaded rise on the upper part of fretboard and I couldn't get the action where I wanted it. TBH, the frets were actually in pretty good shape and I wouldn't have touched them if not for the fretboard rise. Some slight grooving/flattening but nothing that impacted playability or setting proper intonation and that was after 25 years of regular use. Its true that flats are kinder to the frets but I have no issues with doing some fretwork after 25 years of use. Of course it's possible that the fretwire in Squiers is not as good as in regular Fenders so may wear faster but then these are all under $400 instruments.
