When Jesus spoke of the resurrection in John 6:39,40,44,54 he said the resurrection would occur "at" the last day. Is there any significance to the use of the word at rather than the word on.
This is a question about English usage. The Greek original has “en”, which can be translated as “in, on, at” depending on the context. In modern English we normally say “at” a certain time, “on” a given date, but in Early Modern English one often finds “at” where today we would say “in” or “on”. The Oxford English Dictionary, entry “at” IV 29 a, has a quotation for “ate grete day of Jugement” from 1477, and “From 3 at after noone” from 1586.