Well, I would encourage you to try to group his feedings every 2&1/2 hours during the day so he's still getting the same caloric intake but grouping it so that sleep happens at night. This is what I've done with all 5 of our kiddos and will do with our 6th as well.
You can read the first of my seven-part play-by-play here if you're interested:
(The same basic principles can apply even tho you're starting later)
Nighttime sleep and sanity are possible. I wouldn't be able to survive long without a good nights sleep. So please no flames but this is what has worked -consistently- wih a variety of sizes and personalities, to get us all sleeping at night sooner.
Jess, Happy wife & mom to 6 fun kids (ds11, ds9, dd7, ds5, ds3, and precious lil' ds born @ home 2/20/13)
I aim to encourage Christian women at Making Home