How do i convince my hubby were ready for a baby.

My hubby and i have been married a year and have been together 2 1/2 years. He has a 5 year old from previous relationship and the baby mama makes it impossible to see his son. He is at a point where he has just given up on trying to see him because the mother is making it hell for us. But i also feel like hes given up having kids. We discussed it and ge told me when i was 24 then a friend of ours brought up the topic and he said 25. I dont know if hes gonna keep adding years. Im only 22 but he is 27. What can i do?