"How would you handle 3 different customers at once?"
Sigiloso
You wouldn't. If you are already tending a customer who has an appointment set it's vital that you make that guest you're #1 priority. Politely let the other guests know you're currently with another client. You will be with them as soon as possible. If another sales consultant is available and can offer assistance, Introduce sales consultant and let him/her handle the guests needs.