nix could get out of his at 6mths .... but i have the tray as well and he sits in it now to eat sometimes when im too lazy to drag over the high chair ..

but as soon as they have good neck control they can use it .. but i think 18mths is the limit .
but either way you get a good 6mths+ usuing it ... its small so you can chuck it in the car when visiting ...

just dont let your baby near it with a pen ....... mine has artwork all over it now and i dont know how to get it off ...