my 14 week old seems to be ready for solids. h...

my 14 week old seems to be ready for solids. he is getting hungry 1 1/2 hours after bottle feed. he sleeps through the night 90% of the time, but he has a 350ml bottle before bed. his daily bottles are 150 -180mls (3 times a day then his night bottle). he is 8 kilos already (so the size of a 6 month old!). i know the suggestd age to start is 6 months, but 4 months is ok. has anyone else started at 3 1/2 months and why? my DS just doesnt seem satisfied/full anymore after a feed which is affecting his day sleep and making him cry more than ever.