If you are going to reduce a feed make it the 3am one, he should be hungrier when he wakes then. Drop 1oz every 3 nights and see how it goes, he should be able to add the oz you drop to the day.
The dreamfeed needs to be done between 10 and 11pm, later than 11 can disturb sleep as much as help it. It doesn't matter if it's not 4 hours from the last feed, it's meant to be a top up feed to push them to sleep longer so if they will take a full feed great, if not they will take what they need.
from the times you posted, is the 8am feed at wake up? If so, the 7pm feed may be a bit early. You need to aim for a 12 hour day/ night so if you want a 7pm bedtime then a 7am wake-up is a good time to start to get the feeds spaced out to 4 hours.
Laura