What size boots should I buy ???

Monique

I found some cute combat boots online for my 19 month old of course it’s to hot to wear them now so I want to buy them and buy them up for the fall and winter season but I don’t know what size to get she is transitioning into a six in about a month and a half should I get a size 6 or 7 in boots I am purchasing them from children’s place if anyone knows how their shoes run