My first son has a CHD and understandably he didn’t like to be on his front much. He didn’t roll, crawl or walk till really late. But you could stand him up again the wall from about 20 weeks, he stood solid as a rock. He didn’t really baby babble and he doesn’t talk much now. Won’t say his yes or his own name but can name all the different dinosaurs. Still not potty trained at almost 3. My second baby loved tummy time, first rolled at 3 weeks and has been crawling for months. He pulls himself up and walks round the furniture and can walk with a walker. This morning I caught him just standing up on his own in the middle of his cot! Waves, claps and you only have to smile at him for his to give you the biggest cheesiest grin. He says Dadda, mumma, and bubba. Won’t stand against a wall though. He is exactly one month older than Ronnie. Just to show how different they can be. If he isn’t encouraged to do the first things chances are the next stage things are going to come later.