You're right, it's not synchronous! I looked back at our development notes and it seems like we were seeing about 15 minutes, generally, between creation of the

You're right, it's not synchronous! I looked back at our development notes and it seems like we were seeing about 15 minutes, generally, between creation of the manual invoice and finalization/payment. But that was using our test, not production Stripe API keys, and was a fairly small set of anecdata. I don't have better data because we ended up not rolling out any features that required manual invoice generation.