The nearest expiration date for Los Angeles CARBOB Gasoline (OPIS) vs. RBOB Gasoline Futures (Mar 2017) is Mar 31, 2017.
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 Los Angeles CARBOB Gasoline (OPIS) vs. RBOB Gasoline Futures (Mar 2017) before Mar 31, 2017.