The term for due diligence is normally 3 weeks, and closing is usually in 4. Due diligence starts when the deposit is made, which follows the the written Offer to Purchase having been signed by buyer and seller. This document will have the contingency points detailed out. Some properties have no contingency points, some have several, it depends on the property. This is one of the more important areas where you, the buyer, have to rely on the expertise of your broker.