The nearest expiration date for ISO New England New Hampshire Zone 5 MW Off-Peak Calendar-Month Day-Ahead LMP Futures (Mar 2013) is Mar 29, 2013.
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 ISO New England New Hampshire Zone 5 MW Off-Peak Calendar-Month Day-Ahead LMP Futures (Mar 2013) before Mar 29, 2013.