Pertaining to the future rapture, Acts 4:9 states "There remains, then, a Sabbath-rest for the people of God . .".  Then concerning time
of year, or which appointed feast this rapture might happen on, consider Leviticus 23 wherein God lists His appointed feasts.  As to
the Feast of Trumpets, it is said in Leviticus 23:24 "On the first day of the seventh month, you are to have a day of Sabbath rest, a
sacred assembly commemorated with trumpet blasts."

Also regarding the Feast of Trumpets there is 1 Corinthians 15:52 which state, 52 In a moment, in the twinkling of an eye, at the last
trump:  for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed."    This indicates a series of
trumpets which there is preceding Rosh Hoshana again indicating this feast as the possible time of the rapture.