Just going with my first instinct I always thought if BLS was going to work you need to start with it. Because I think (I might be wrong) that the whole point of not doing spoonfeeding was so that you don't override the gag reflex. I would think that a baby that has never been spoonfed puree would be better at controlling their intake of food and more cautious about what they put in their mouth, so less chance of choking.
That said, I think by 8 months old, if they are sitting up unassisted and have good hand to mouth coordination they are still capable of finger food regardless of having been spoonfed purees ITMS. Because BLS or not, one day they will be transitioning to finger food anyway!!
And I understand it to be choking is silent and gagging isn't. Although I have no experience because even with BLS my DS never gagged!
Good luck with finger foods!