Welcome Week and Registration will begin nine days prior to the start of term. The start of term is the 26th of September, and undergrads who are living on campus will be able to move in to their campus accommodation as of the 17th of September.
Personally i advise moving in on the 18th, as the sunday is often the day where the most amount of people arrive. I also believe that the Saturday evening bar crawl has not been scheduled for this year (however you should check your welcome week calendar), and the lack of this event may make the first night a tad dull.
I would suggest taking advantage of all of the Welcome Week tours and tutorials, as these will help you with managing with your departmental issues, and library navigation. IT IS ALSO A GOOD WAY TO MEET PEOPLE ON YOUR COURSE!!
Edit: Also, watch out for Fresher's Fair, it will be the prime spot for free food and is your only hands - on chance to sign up for societies (otherwise you have to sign up via Kent Union).