I would call a short nap at less than 1.5 hours, and possibly just judge how tired your LO is in the evenings. There are nights when DS seems more tired than usual, but we would just get into pj's early, give him his lovey (paci) and read with him a little longer. BT would only be 15 minutes early, but this seemed to help keep him calm. He doesn't fall asleep anyways if we put him down too early.
If the EW's are recent, a gro-clock could be very helpful. We use an imitation one which turns the light on at his normal wake-up time. He started a bout of waking up 45 minutes early for about a week, so we got the clock and insisted he couldn't come out of his room/ it wasn't morning until the light came on, and he stopped EW'ing, once he got that message (only took a few days).
I would also say to keep your interaction at a minimum in motn during a NW, as this also helped us shorten NW's. We found that talking to DS and asking him what was wrong kept him up for longer, than simply giving him his paci, a sippy cup with water and whispering go back to sleep with a gentle pat. When we were asking him what was wrong he was up for longer.
