19 months old
We were considering getting Corinne a kid size chair but she found a creative way to repurpose her Winnie the Poo doll instead.
As you might guess, Corinne smashed this tower down two seconds after I took this picture.
As you can see from her growth chart Corinne is getting tall. At her 18 month doctor visit she jumped up to the 75th percentile for height.