As he's so young, I would give a big handful of pellets twice a day, rather than a small handful. Spring greens will be good for his growing bones too, as they have lots of calcium in - just try him on a mouthful sized bit at first, and slowly increase over a couple of weeks it if it doesn't upset his stomach - my adult rabbits have about a medium leaf a day each, a tiny knob of brocolli (it can cause wind) and a little chunk of carrot for a treat.
I give them fresh hay twice a day, as they often don't eat it if it's left from the day before - they need roughly their body-size in hay every day. I use science selective pellets, and they have a small handful twice a day - although Maa has a big handful as she seemed very skinny on low pellet rations.