N.R.
I went thru this with my (now) adult daughter and she lived with us when her son (with a cleft palate) was born, so I've been thru this twice. They both had clefts of the soft palate only, and no cleft lip. I found that bottle feeding them as babies was harder than giving them solids. I know this sounds strange. When I started them on small solids (to begin with) they were somehow able to swallow it with their tongues and it just went down without coming back up out their nose (like liquids did). With liquids or a bottle, they had to suck, rather than use their tongue & throat muscles. Without knowing the extent of the cleft, I would start out with small, soft, solid foods (canned fruits cut up small, etc.)and see what happens. Be prepared that he may not like the texture of solids at first (nothing to do with the cleft), just like many non-cleft babies do. There are Cleft Palate support groups (go on the Internet), also. My daughter had her one and only surgery at 17 mo., and her son had his one and only surgery at 15 mo. Both were very successful with no speech or other problems later. Both surgeries were done at Denver Children's Hospital, where we lived at the time. We're now in West Des Moines.
I forgot to mention that you start him the same as any other baby, with a spoon, or let him pick up his own small pieces off the high chair tray, etc.
Feel free to contact me with any questions.