Not sure on your history and if you've been doing any type of routine, but it totally depends on the l.o. for how long they can go. At that age, my dd was eating every 3 hours or so, and going one longer stretch at night, I think, that was sometimes 6 hours.
Can you tell when when your d.s. is hungry? Do you see any cues? Rooting, a certain cry?
~Kim