Question about a "bouncer"

Ambur • Married with (3) children. 21. Leo.
I was just wondering what age you are supposed to start with the bouncers? I have a baby Einstein and I put my almost 4 month old in it and he likes it I put a pillow under it and he likes the music and stuff and I put a blanket in it cause he's a little small but what's the age you're "supposed" to wait until?