“For N o’clock” or “by N o’clock?”

When you have an appointment, do you say you need to be there “for” or “by” the scheduled time?

I have always said “by.” I need to be at the office by nine o’clock.

My husband, however, has always said “for.” He needs to be at the office for eight o’clock.

The first time I heard it, I mentally stopped, stock still. “For?” Surely you mean “by,” right? I didn’t ask, though. I just made a note and kept listening. Sure enough, that’s the phrasing he always uses. He was born in MA and grew up in RI. He’s not British, which this usage would seem to suggest (it’s “exclusively” BrE, according to Algeo’s British or American English?”: A handbook of word and grammar patterns).

I’ll suggest it may be less “exclusive” than his research led him to report. He states¬†“0 iptmw in CIC texts” for AmE. In English (AmE, precisely), that means zero instances per ten million words in the Cambridge International Corpus. I can swear to the existence of three American English native speakers (my husband and his two daughters) who use “for” where I use “by” in this particular construction. Is it a spoken AmE thing, but not a written AmE thing?

I’d love to hear from linguists who have experience with this wording. Is it as “exclusive” as Algeo says? Or are there other AmE speakers (perhaps from New England, or perhaps only in that little bit of MA and RI) who use this? I’m a corn-fed Midwestern gal of Frisian extraction. This British thing . . . I didn’t grow up with this.