We have the Snugabunny, and it is a lifesaver for me to get anything done (especially showering). I started using it early on. It kept her upright from a very young age, unlike some less supportive ones (my MIL has one at her house that DD just kept sliding to the side in).
In case you are referring to a jumper, my first started using his around 4 months. His feet didn't touch the ground so I stacked up some books under him for awhile.
Re: Bouncy Seat Edit:jumper
I have no idea if there's an age they need to be before going in it. I put DS in it at about a month old.
In case you are referring to a jumper, my first started using his around 4 months. His feet didn't touch the ground so I stacked up some books under him for awhile.