That will be very specific to each business and each consumer.
That's a big problem! Fiat currency is universally useful to to every legitimate business and consumer, and btc needs to be as well if it's to have a long-term role in the world.
That's an almost irrelevant minority from the perspective of long-term success for bitcoin. Same with basically everything sold on silk road.
That's because today there is no competitive advantage to bitcoin. For one, you're telling consumers to use a payment method that is objectively worse for them. There is no insurance at all for the consumer with btc payments currently. If they use Visa/Mastercard/Paypal to buy stuff from me, Visa/Mastercard/Paypal will protect them to some degree. As a merchant, that is incredibly valuable, because I'm not Amazon. I don't have a reputation large enough to precede me, and so I depend on the payment protection that Visa/Mastercard/Paypal offer my customers to ensure that the first time they buy with me (ie before trust is established), they can feel indisputably safe.
As an example, I just bought a $1300 camera from a store in Taiwan over Ebay. I'd never have paid them in BTC, because if they screw me over, I have no recourse. With Visa I have recourse, and Ebay adds an extra layer of protection for me on top of that.
That's the kind of thing that bitcoin needs to explain to consumers. If it's not there, then there's no reason at all for most consumers to use bitcoin, and it will remain a niche currency that isn't useful for most purchases.