We offer a very similar service at hullopress.com (Portuguese site), and we're yet to see the day when a client approaches us with all of their content ready for upload, and even have it ready for us within a week. Another thing to be wary of is clients asking for additional features, which are never as simple or quick to implement as they think. Barring that, our experience tells us that delivering a site in one day is perfectly feasible. Best of luck!