The nearest expiration date for European 3.5% Fuel Oil Cargoes FOB MED (Platts) Futures (Jul 2016) is Jul 29, 2016.
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 European 3.5% Fuel Oil Cargoes FOB MED (Platts) Futures (Jul 2016) before Jul 29, 2016.