When was the paper of bitcoin announced?
According to the mailing list archives, the mailing list received Satoshi's email at Fri Oct 31 14:10:00 EDT 2008. However the mailing list is moderated so perhaps the email was not received by everyone until a day later on November 1st. The first response to the email was sent on November 2nd, so it may be that the email was not forwarded to the list for a day or so.