when my highchair arrived, my daughter was a little over 5 months old, although the product states from 6 months + she fit in well, and was well supported. assembly was fairly easy, the legs needed to be attatched, and armrests, but i managed these on my own in no time. so this point was a bonus...
HOWEVER...
on either side of the chair are two red 'locating' clips, that when you pull up the backrest of the seat, are supposed to locate into holes on wither side. i don't know if this is a design flaw, but 9/10 one or both of the clips wouldn't locate 1st time, and often not at all, resulting in the seat having to be wiggled, collapsed, put back up repeatedly. if this was a feature that wasn't important then i would have just left it, but this is the MAIN support of your child, and i wasn't prepared to have this fail on us. the legs have to be fully apart to have the highchair locked correctly, and despite several attempts, i simply gave up and sent it back where it came from.
i have since bought mothercares version of the same design, which works and locks perfectly every time in the manner this one should have. and i saved £10, bonus.