The nearest expiration date for NYISO Zone C 5 MW Peak Calendar-Month Day-Ahead LBMP Futures (Jul 2017) is Aug 2, 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 NYISO Zone C 5 MW Peak Calendar-Month Day-Ahead LBMP Futures (Jul 2017) before Aug 2, 2017.