I'm unsure of which to use, I have a events calendar which uses the GET method, if a user manipulates the url to navigate to a month prior to the first event's month I issue a 301 and redirect them to the first month. However, if a user attempts a url after the last event's month I need to issue a temporarily unavailable header prior to redirection. I'm a bit unsure if I should issue a 302, 303 or 307.