The nearest expiration date for PJM Western Hub Peak Calendar-Month Real-Time LMP Futures (Apr 2016) is May 6, 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 PJM Western Hub Peak Calendar-Month Real-Time LMP Futures (Apr 2016) before May 6, 2016.