This is always the debate when you work alone. We all rely completely on the phone and our referrals. Over the past 27 years I have developed this:
Strong and excellent referral- I will be 100% honest and tell them I am out of town at a conference and I will be back on _____ date. How about we schedule for ___.
Weak referral - Early in my trip - I am out of town at a conference and will be back on _____ date. How about we schedule for___.
Weak referral - Late in my trip - My schedule is currently full but I am available on _____.
Strong referral - Late in my trip - I am completely full until ____. I can try to move a couple of things around and fit you in on _____.
I am always steering the inspection toward when I want and can do it.
The least desirable is having another firm help you out and take your business. You will take theirs when they go away (hopefully).
All of these provides the customer with a solution to use you as well as it creates a mental demand upon your services. This will help sell you and you business.