When to start?

When is the time to start giving babies purées 3 times a day? My son will be 8 months old next week and I am giving him purées twice a day right now. He pretty much hates everything besides sweet potatoes squash and bananas and when I do feed him he’s so scared I’m gonna give him something gross he won’t open his mouth until he knows it’s one of those three foods, which is why I am still doing twice a day. Anyone else have a picky baby? What did you do for feedings? I also wanna mention that my baby wakes up late and doesn’t eat breakfast until like 11