HTTP Status Code for Resource not yet available

I have a REST endpoint accepting a POST request to mark a code as redeemed. The code can only be redeemed between certain dates.

How should I respond if someone attempts to redeem the code early?

I suspect HTTP 403, Forbidden, is the right choice but then the w3c states that "the request SHOULD NOT be repeated" whereas in this case I would anticipate the request being repeated, just at a later date.