D.C.
Hi H.,
I'd wait until your son develops the pincer grasp on his own, then start with the puffs. If you try them, you'll notice they dissolve in your mouth right away. My daughter developed the grasp somewhere around 9 months old, I think, and she started on solid foods then. She liked black beans, and canned vegetables (I bought the no salt added kind).
Give him another few weeks, and see how he does. Put some puffs on his high chair and let him play with them, and put them in his mouth if he wants to. If you have him on stage 1 foods, you may try gradually moving on to stage 2 and 3 foods before you try anything chunky so he does get used to the texture. I'd say the most important thing is to let him be the one to decide he's going to pick it up and eat, rather than have you feed it to him.
Good luck!