Jackson was 26 months when Leo was born, so approx 16 months when we convieved. He didn't really make the connection that we were going to have a baby, but he would point to my tummy and say baby, so he knew there was some connection with my tummy and a baby. We named DS#2 early on, so we would refer the the baby as Leo instead of the baby and then when Jackson came to meet Leo in the hospital it was like a lightbulb went on and he was thinking "Oh, so this is Leo!" I think that helped, he was very sweet and kept forcing himself away from the fire engine that "Leo had bought him" to give him little kisses.