This is another excellent question. This part of the equation largely depends on you and your client. After all of the website content is evaluated, and feedback is provided, the changes can then be made.
Depending on the number of changes, it could be a while until the site goes live. However, if you have no additional tweaks that need to be made and you like the website precisely how it is or you only have minor changes to make with the copy, the website can go live immediately.