Typically, a home inspector is contacted immediately after the contract or purchase agreement has been signed. Before you sign, be sure there is an inspection clause in the sales contract, making your final purchase obligation contingent on the findings of a professional home inspection. This clause should specify the terms and conditions to which both the buyer and seller are obligated. It's a good idea t include a 7-10 day period in you purchase agreement for the inspection to be performed. Often the better inspection companies are booked a 5-7 days in advance.