I'm sorry but your challenge is time limited which is not allowed under the current guidelines.
Please read 2.12. Challenge caches
https://www.geocaching.com/help/index.php?pg=kb.chapter&id=127&pgid=206#timeLimited
9. Time-Limited
Not acceptable
Time-limited caching: as in some number of finds per day, week, month, or year. Example, Busy Day, 50 finds in a day, 500 finds in a month, etc.
(new 2016)