Have you looked at InterCaribbean? They are booking flights online and already flying to EIS. They have more flights and have been more reliable in my experience. Air Sunshine has never left me at SJU but they almost never stick to their schedule. Be aware, they will weigh both your checked bags and carry-on and will charge you for anything over the published weight (I think 35 lbs). Sometimes they are a couple of hours late but other times they've been very early and said they were about to leave without me.

Air Sunshine does not have any space inside the secured area of the terminal so you wait by the ticket counter. There is no seating space so I usually wait outside near the drop off curb. If they decide to leave an hour early, it's tricky to know. Then they walk you thru the ticketing area, clear you at a strange security area used by employees, walk you thru the bowels of the luggage area and out to a shuttle bus. The advantage is they sometimes combine flights with VG and you get to land and clear in Virgin Gorda! Very cool dirt runway landing and much easier to clear immigration and customs.

On another note, the new curfew info came out late last night and no change was announced to the opening date.