I really would caution you against going to a 4 hr feeding schedule with such a young baby. It used to be the orthodox view that 4 hour schedules were the way to go and everyone started on them and then found they had supply problems. It's one of the reasons that breastfeeding rates were so low in the UK beyond the first few weeks in the 1970s and 1980s. It's only more recently now that we know it's not advisable that breastfeeding rates have picked up. Breastmilk is digested in under 3 hours. Some young babies may not exhibit clear hunger cues and will appear not to mind - especially the sleepy ones. The feeding times you are describing are not unusual and you just have to try and keep him awake if you can. Young babies that are very sleepy can end up feeding less and I wouldn't aim to schedule less feeds.
Here's a quick quote:
"The Womanly Art of Breastfeeding" by La Leche League International says "The more the baby nurse effectively, the more milk there will be. Understanding this 'golden rule' of breastfeeding is the key to an abundant milk supply and a contented baby. Years ago, mothers were often told to wait four hours between feedings so that their breasts would 'fill up'. Many a mother and baby had a short-lived breastfeeding experience due to this well intentioned but erroneous advice. It is now well understood that milk is produced almost continuously, and that the more often and effectively the baby nurses, the more milk there will be. Thus, the mother of a baby who is nursing every two hours will have a bountiful milk supply, while the mother who is trying to 'hold off' the baby and nurse only every four hours will have considerably less milk. Frequent and effective sucking at the breast signals the mother's body to produce a correspondingly increased amount of milk.""
This is still very early days and your milk supply needs to be established. You have some mega-growth spurts to come!
Talk to your doctor and preferably a lactation consultant too if you are worried.