RFC 2616 date/time stamps

Current date:

Thu, 23 Mar 2017 18:09:09 GMT

30 days from now:

Sat, 22 Apr 2017 18:09:09 GMT

365 days from now:

Fri, 23 Mar 2018 18:09:09 GMT

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