Instantly. Zero exchange risk for the merchant (Bitpay considers their hedging strategies as part of their core-competence-- they don't always convert to USD/Euro/GBP [1], they sometimes stay long bitcoin). All payments for the day are aggregated (in USD/Euro/GBP [1]) and sent to the merchant (as long as it's more than $20, I believe. So it's much quicker than credit cards (and don't forget money from credit cards can be automatically pulled from the merchant account up to 120 later, whereas these ones are irreversible.) [1]Note: This is why it's easier to say "fiat" when referring to national currencies. :)