Since you're just sorting them, a module is just going to slow you down a lot. How are the dates stored?

Seconds since epoch? Just sort numerically.

Using one time zone? Your goal is to rearrange into a lexically sortable format (e.g. %Y-%m-%d). This might require modules depending on the specifics on the format. Once you have that, you can sort lexically.

Using different time zones? Your goal is to convert them into a single time zone (e.g. UTC) or seconds since epoch. This might require modules depending on the specifics on the format. Once you have that, see above.