Hi,
My LO was like that until just a couple of days ago. I have not really pushed finger food, just letting her play with a spoon instead. Last weekend we had dinner out and I gave her a piece of cucumber to nibble on (I was holding it). Toast, sandwiches, banana etc. have been squished while I retrieved bits to put in her mouth, but she has just got the hang of holding toast fingers so that she can nibble on them, and now everything gets bitten (including the spoon - and my finger). I think it is just something that seems to come overnight when they are ready. Will he bite on food when you hold it for him? Try not to stress about it or he might pick up on that.
Vicky