Is there a way to cause git-reflog to show a date alongside each entry?

Per the man page, you can use git log options, e.g.,

git reflog --pretty=short

git reflog --date=iso

You can use a custom format:

git reflog --format='%C(auto)%h %<|(20)%gd %C(blue)%cr%C(reset) %gs (%s)'

In the above format, %h is the commit hash, %cr is the relative committer date, %gs is the reflog subject, and, %s is the commit subject. Look at the git-log docs for other possible placeholders. For instance, using %ci instead of %cr will show absolute commit dates.

You can save this in your ~/.gitconfig using a custom pretty format and refer to it via an alias:

[alias]
    rl = reflog --pretty=reflog
[pretty]
    reflog = %C(auto)%h %<|(20)%gd %C(blue)%cr%C(reset) %gs (%s)

You can use the --walk-reflogs variant of git log:

git log -g

This is rather verbose by default, and prints the date among other things. You can format it with the standard --pretty= flag.

You can also use the reflog command directly with the --pretty= flag to format the output.

git reflog --pretty='%cd %h %gd %gs'

In the format above, %cd shows the commit date to the left of the normal reflog output.

Tell git in what format, either counted reflog entries or timed reflog entries, i.e.

git reflog @{now}    
git reflog @{0}