How long after a house valuation does the sale complete?

Simple you have found a buyer,they have secured a loan to buy your property,the lenders valuer has made an inspection to ensure the loan against value is secure,your buyer will get an advance in principle subject to the solicitors acting on behalf of the buyer and lender meeting all conditions.Your buyer will tell you the loan has been approved and they wish to proceed.Have you not talked to your own lender or conveyancer,are you not looking now or will you waste your purchasers time and money,sorry to be a little harsh but the people interested in buying your place have spent money and quite a lot of it probably �500 so far.