Start rebase process with
git rebase -i HEAD~<number of commits to rebase>
Editor is shown with all commits listed. Change all pick
to edit
for the ones you want to update. Save and exit editor
Then for each commit rebase do the following:
Set environment variable for GIT_COMMITTER_DATE to the date you want to update to, i.e:
$env:GIT_COMMITTER_DATE = "2020-05-05T14:00:00 -0600"
Next do a commit with the updated dates:
git commit --amend --no-edit --date=$env:GIT_COMMITTER_DATE
Then continue to the next commit to rebase by typing:
git rebase --continue
Note - These examples are using PowerShell as the command line