git commit – setting timestamps into the future

You should wait a bit.

Or you can do this:

/tmp/x 604% env GIT_AUTHOR_DATE='Wed Dec 19 15:14:05 2029 -0800' git commit -m 'future!'
[master]: created 6348548: "Future!"
 1 files changed, 1 insertions(+), 0 deletions(-)

/tmp/x 605% git log 

Author: Dustin Sallings <dustin@spy.net>
Date:   Wed Dec 19 15:14:05 2029 -0800

    Future!

Note that there’s both an author date and a committer date, so be sure to set the right one (or both).