The puffs will dissolve in their mouth you don't have to wait for teeth, and 7mos is old enough for those kinds of snacks. The only difference with the different stages is the consisitency. It gets thicker and chunkier. But thats about it. There's more variety as they get older but I mean, but thats all. Stage 2 right now should be fine. I started my son on solids at 5mos or so too, and then he went thru them kinda fast. The general rule of thumb for the different stages is stage 1 is from newborn and older, and stage 2 from about 6mos, and then stage 3 from 8mos. But each baby is different so she will let you know when its time to try other foods. But your doing a good job momma!
I have a son who is turning 1 next week!