The nearest expiration date for Singapore Jet Kerosene (Platts) Futures (Aug 2013) is Aug 30, 2013.
The best time to sell a futures contract is when you've already made money on the investment, but still have plenty of time left before the expiration date. Thus, a good option would be to sell Singapore Jet Kerosene (Platts) Futures (Aug 2013) before Aug 30, 2013.