I actually started putting my little one in his own little table as soon as he understood which was maybe at around 10 months old. Another option so that your daughter could sit at the table with you guys would be to buy a seat that attaches directly to the table.
A chair that attaches directly to the table:
This is what I bought for him over a year ago:
http://www.shopwiki.com/detail/?q=Toddler+Cube&s=653039&o=357216170&d=Jonti-Craft+Toddler+Kydz+Cube+ChairDirk sitting at his own table set. Wow he is messy! He looked so different then! He has like balding hair or something!!!!!:
Dirk sitting in the chair and goofing off with his one leg: