We were there in October with our 7 month old DD. I remember they did have Nestle Good Start but I am not sure which types. Nestle is a WDW sponsor so the Baby care centers do feature the Good Start products (a cast member told me that they also carry Similac and Enfamil but they are not displayed because of the sponsors - you have to ask a castmember for them). The things they stock are actually quite impressive - they also have a nice selection of baby food, baby bottles, and baby first aid needs. A word of warning though, everything in the Baby care centers was twice as expensive as outside the parks. I wouldn't rely on it. When we went we brought a full supply of formula (cans for the parks and bottles when in our room) with us (DD was on Similac).
Also, I just want to add that the Baby care centers are wonderful! I wish they had these everywhere I go with my baby! Have a great trip!