Cheerios vs Puffs

We have been feeding Dov, who is now 5 1/2 months old cheerios for about a week. With Eliott, I think we waited until he had 4 teeth which would have been at 9 months old. Shia had 6 teeth by 4 months so I was less concerned about his eating abilities so he also started cheerios early. Dov only has 4 teeth. He seems to really love cheerios and also rice krispies so this weekend I bought him a container of those baby puff things. What a disaster! He kept choking on them. I can't figure it out... he can eat the "big kid" food fine, but cannot seem to eat the "baby food". We will not be buying anymore puffs. He will just stick to cheerios and rice krispies which I think is the cheapest option anyway!