There's no way to tell exactly what day it will end, but the admin has bad intentions by cashing out his STP starting when the program is so young. You can go in and jump out, but the risk is high with an admin cashing out STP consistently on a daily basis for so long.
Oh still cashing out to this day? There's no case where people running these sites would cash STP but not plan on closing up?
It is really dependent on the rate of exchange. I have seen many admins exchange a few thousand here and there and not close for quite a few months. Difference with Rockwell and other admins who are planning their end game is the exchange of many thousands on a daily basis. When he hits his magic number that he wants, the payouts will stop.