He's 3 years old. He's at daycare 5 days a week so the times below will be approximate. He may miss a nap (perhaps 1 per week).
His schedule was:
Wake: around 7 am (I have to wake him up)
Nap: 12:30ish to 1:45ish
bed: ~8:30 pm
On week-ends, we usually let him sleep in (so perhaps up between 8 and 9 am). His nap will start later - usually he's asleep by 2:45 - 3 pm and will nap for roughly 2 hrs. His bed-time will move closer to 9 pm but he's usually pretty good about going to sleep even though he woke up from his nap just a few hrs earlier.
Since developing this fear, he sometimes isn't asleep until closer to 10 pm

We are finding that he's avoiding going to bed (e.g. doesn't want to get out of the tub, need to go to the potty, etc). Even before we get him to his room, he's already saying that he's scared of thunder or froggie...
I had looked at the wi/wo method the other night. My main concern is that as soon as I (or DH) leaves the room, he's instantly screaming and saying he's scared. I was thinking that I may need to help him overcome his fear but I'm not sure how to go about doing this (and hopefully his sleeping skills won't degrade too much.)