how old before

[trinityrocks]

they should use a highchair????

When they can sit up by themselves usually. Depends on the high chair though. You can wedge them in with cushions a bit earlier if you like.
My 5 month old has just started going in his. Not to eat, but to play with things on the table.

High chair. reckon umm well 7 or 8 months. remember starting weaning at 6 months an dd was in buggy or bumbo thingy. but still lolling aroung a bit

does depend on the highchair like spidermama said - for example the tripptrapp is v simple and doesn't have any recline options, so they need to be completely supporting themselves as opposed to a fancy one where they are quite cozy

dd2 is 6.5 months and not sitting up yet - I feed her in her bumbo on the table or in my lap. our highchair is a tt, so maybe in a month or two maybe?
good luck! how old is your baby?

shes 4 months but pulling her head and shoulders off her bouncy chair and bouncing in a door bouncer totally supporting her head and shoulders.
she is also rolling all the way over and reaching out and grabbing things all the time, I thought that if I got a Chicco one then with all the rclining options and the height options of the tray that she could just play in it )

when they can sit up properly

1st stage car seat or bouncy chair is a good intermediary. It can be quite tiring for them if they're a bit young. Monkeychops went in his around 6 months.

depends how much you want to spend. Reclining options cost, and you won't need them once she can sit up (i.e. maybe a month or so if she is already trying to lean forward).

Ikea do a great one for about 15 quid. Not too big either which was a problem for us at the beginning.

the chicco one is GREAT for younger babies... we used it from when dd was 5 months cos she was too big for her bouncy chair.

HOWEVER... is it a bu$$£r to clean. at 26 months we have just changed to a booster seat, and for the last 18 months or so i have been constantly wishing i had got a different, simpler chair as there are millions of crevices in the chicco one where food hides, no matter how dilegently you clean it.