The nearest expiration date for European Diesel 10 ppm Barges FOB ARA (Platts) vs. Low Sulphur Gasoil Futures (Aug 2015) is Sep 2, 2015.
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 Diesel 10 ppm Barges FOB ARA (Platts) vs. Low Sulphur Gasoil Futures (Aug 2015) before Sep 2, 2015.