Don't have a date...The last Apostle to write was John...The book of Revelation...The book of Revelation goes up thru the final judgement and off into Glory...That's the end of the canon...
And the date? Well, I'll tell you. It was in the fourth Century AD. A Church Council (those Catholics and Orthodox) authorized the Canon that you now know as the New Testament. They threw out books as uninspired or not Apostolic. The NT you read from was approved by a Church Council. What each community had prior to that was a compilation of letters and books that included both what would become the Canon, but also non-canonical books like the Acts of Peter or the Acts of John or the Clement's letter to the Romans.