Legal Question in Business Law in Georgia

First of all, the non-legal advice. Your question indicates an anti-consumer policy that will loose you customers and cause your problems and damage your reputation. You will, in almost every case, score points and gain repeat customers by contacting guests. I'd also keep items far longer than 72 hours (30 days would be far more reasonable).

Now the legal advice.

Many cities and counties have unclaimed property oridinances, so your local ordinances must be consulted. In some cases you must turn over such items to local authorities. Second, if the item is abandoned

Third, notices you post on a wall probably do NOT protect you (but they will antagonize some customers by showing a bad attitude from you). Signed language that each customer signs or initials at check in on a form (and have a lawyer draft it) would be far better legally.