How old are babies when they really start to bounce in bouncer seats?

My son Noah is 3 months and 3 weeks old. He will sit in the bouncer for a little while at a time and he will sometimes kick around a little, but he never really gets it going. My older son is 7 and when he was a baby he would go wild in his bouncer. Also Im not sure if his bouncer may be messed up, because a friend accidentally smooshed it, we stretched it back out and re-shaped it but its still a little uneven. So, how old are your babies and how do they bounce?