When to start finger foods?

I am a first time mom and my son is only a few days away from turning 7 months old. He has been eating puréed baby food since around 5 1/2 months old. He does well with it and often tries grabbing the bowl. He also sits up unassisted but he is not crawling yet. I was thinking of starting him out on easily dissolvable foods first; such as the Gerber puffs or teething wafers. But the boxes recommend they be crawling. When did you start giving your baby finger foods or puffs?