One year per inch of thickness is the usual rule of thumb for air drying. Can vary by species, and the thicker the wood, the longer it will usually take to dry (i.e., 12/4 or 3" thick wood might need four to five years). This is one reason a lot of us buy rough wood whenever we have the opportunity and figure out what to use it for later.
Most basements are far from the ideal environment: too cool, too damp. An outdoor shed, enclosed enough for weather protection but open enough for good ventilation, is best.
Plan on investing in a moisture meter. The current issue of Woodworking Magazine (the slim one with no ads) contains an excellent comparison review.
Only ways to expedite the process is to saw the wood thinner, or have the wood dried in a kiln.