Let's split this into two parts, because they take very different amounts of time.
The technical part. On a server subdomain, the site is up in minutes: the space, admin panel, and design are already in place. On your own domain, there's DNS propagation to wait for — usually anywhere from a few minutes to a day, and that's not up to us, it depends on how fast the records propagate.
The content. No one can honestly give you a timeline here. A site becomes real with two pages — what you do and how to reach you — and those can be written in an evening. Everything else gets added as you have things to say.
You won't see promises like «a site in 24 hours» here: you really can put the shell together fast, but an empty shell doesn't work, either for visitors or for search. If you don't have time to write, studio partners handle content — Studio help.