racerwesu
use a pda, making it harder for them to see your schedule

Blessed
Hold the book in your hands to read it and tell the client what day and time you can reschedule to and instead of writing it in your book, close the book and write it on a note pad on your desk (and if you do it, write it on your card and give it to the client.) When the client leaves then you write it in your book. (or slip the paper into your book to post later.

BigMug
Maybe a computer style desk may be an option as it has a slide out piece that you could pull out and which they would have to obviously have to lean further over to peek

Grace L
If you wish to take control over your business, perhaps it would be better if you asked your clients their availability dates, and tell them you will be putting it on your schedule but will be temporary until you have verified with them a confirmed schedule via email. Also you can be firm in informing them that data and confidentiality of your clients' are paramount - saying that they would not want other clients to know about their details. You did not mention what your business is about and whether your visit to these clients are on a fairly regular basis. If your visits are regular you can assign them a day, time and date i.e. every 2nd Thursday of the month. Another option would be to let your clients know that you have an appointment setter whom you need to coordinate with to ensure you have not double booked yourself. Then as soon as you have privacy in your office you can fairly quickly confirm their appointment schedule without any pressure from your clients. Perhaps you can consider using the services of a Virtual Assistant who can do this for you. Please do not hesitate to contact me for further questions.

izcrystalblue
Have you considered a Virtual Assistant? Both Google and Yahoo offer free calendaring sites that allow you to enter schedules every 15 or 30 minutes. Just a thought, Tricia Kos, Owner/VA Quality Business Solutions, LLC Your Virtual Assistant Destination