Dd has had toast since she started on solids at 6 months. She didn't really eat much for quite a while but enjoyed sucking the butter off! She's now 7 and a bit months and is getting the hang of chewing it with her gums. Let him try- he'll have fun with it even if he doesn't eat much.
My DS is 6 months, just started weaning, have been giving him toast fingers. Not much eating as such, just sucking etc, but all good, he loves them! I think the advice here in NZ where I am is to wait til 7 months for wheat products if allergies, eczema etc in the family. Haven't tried pita breads yet but evidently they are easier for babies to manage than untoasted bread which can stick to roof of the mouth.