With affordable and ample housing, don't worry about getting in too big of a rush when looking for a Blacksburg apartment. A safe amount of time is about two months. That gives you enough time to look at a few places and pick the one that makes the most sense for your personal situation.
Virginia Tech students are certainly one of the largest rental populations in town. The Virginia Tech website has a great section through the Division of Student affairs that provides information for students looking to secure off campus housing. One of the best pieces of advice it offers is to ensure you read the entire lease before signing. Make sure there are no conditions you don't understand, or which may treat you unfairly.
Blacksburg transit makes getting from almost anywhere in the city to Virginia Tech a snap. In addition, the transit system is free for students, as the transit system is the result of a joint project between the city and the University. Throughout most of the year, riding your bike is also a great way to navigate the small city.
A lot of the best fun in Blacksburg is actually outside the city. The Appalachian Trail passes near the city, and many other great hiking routes provide miles of entertainment for the physically inclined. Virginia Tech is also the site of much of the town's entertainment, including the almost universally supported football team, The Hokies.