M.H.
You should be able to start cereal. Sounds like he's hungry!! I personally had the trouble of being up all night breastfeeding. I started my lil girl at 5 months mixing breastmilk with cereal and feeding with a spoon in highchair first thing in the morning. Then, started using nursery water with the cereal a couple days later. I also started feeding nursery water in a sippy cup with meals. About 2 weeks later we were feeding her baby food squash and sweet potatoes. She ate breakfast and late lunch after her last nap.
I know it seems early to start those things, but my lil girl was hungry and thirsty! She loved the cold water in sippy cup during the day. I put it on the floor where she plays.
Here is a schedule I keep:
6:30 Instead of bottle in the morning, try some cereal (like alot of cereal) and a jar of fruit or veggies. Feed the baby until he is full and won't eat anymore. Then, let him play until nap time.
9:30-10 Bottle and put down for nap. Don't let him sleep longer than 2 hours. You don't have to wake him up necessarily, but open the door and start making noise so he wakes up on his own.
12:00 Feed lunch like a jar or two of baby food. Put some Cheerios on the tray and let him play eat. After, let him play.
3:00 Bottle and put down for nap. Don't let him sleep longer than 2 hours. Again, you don't have to wake him up necessarily, but open the door and start making noise so he wakes up on his own.
Then, Bottle maybe 2 more times before bed time. Keep bedtime early like 7:30 is good. My daughter wakes up at the most 3 times at night when she's teething. Usually though she wakes up at 3:00 for a feeding.
He might like eating and he's old enough to start. Maybe it will satisfy him enough and get you both some sleep!!!
Good luck. ;)