Thats a tough one - you can't go from nothing or little to 3 meals a day! Maybe try two meals and try when you know he is hungry and before bottle which i'm sure you said you are doing anyway, if he gets frustrated maybe give him half a bottle first- maybe if he isn't interested in puree he could try something mixed with his milk like rusk?
If he isn't interested still after a few days maybe you should just wait - follow your instints hun i think hv all have differing opinions. When my eldest was a babe i was told it was fine to wean hime between 3-4 months this time it is 6 - i just go with babes they are all different. Sarah had half a fruit pot today and ate it so quickly then cried for more - i didn't give her more just topped her up with milk, i couldn't imagine leaving it til six months as she is so big and sleeps so long she needs something else - i wouldn't admit it to my hv though lol