feeding

Hi!
I became a proud mom of a big boy on June 24th!
He is now 11 weeks old, 68 cm long and a whopping 7 kg. He's now having 6/7 bottles of 180cc, 6 scoops. At night he sleeps through, about from 10 pm to 6:30 am. During the day he wants food every 3 hours and sometimes even earlier! He takes quite a long time for a bottle, usually a solid half hour to 3/4 hour. This means that with changing and preparing the bottle I'm under the covers for an hour, and 2 hours later the party starts all over again..
Now I heard from someone who works a lot with babies, that he could already start with fruit snacks from 3 months because he is a fairly big baby and is quite advanced in his development. Now my question: is this wise? I myself would maybe like to start with a cereal bottle so that he is fuller for longer.
Anyone with experiences or ideas?
Greetings do