RFC 2616 date/time stamps

Current date:

Sat, 24 Sep 2016 22:33:17 GMT

30 days from now:

Mon, 24 Oct 2016 22:33:17 GMT

365 days from now:

Sun, 24 Sep 2017 22:33:17 GMT

These are they dates you want to use in HTTP headers, such as Last-Modified and Expire, on the Internet.