In my experience it took them 2 days to process my order and get the modem shipped out.
The modem arrived within 3 days and I still had a few days left before the activation date.
It usually takes a week for activation of your services, as the tech needs to come out to the central office and turn your dsl on.
So even if you got the modem sooner it would do you no good to hook it up because you wouldn't have internet.
Also it's recommended to wait until after 8:00 PM on your scheduled activation date to setup your modem.
That's what it states on centurylinks website.
http://www.centurylink.com/help/help/index.php?assetid=135