I'd spot-treat it and give him my honest estimate of what he might expect, and what to do about it. After all, if he does get termites somewhere else, I want him coming back to me. And make sure the guy that shows up is an exterminator, you'll probably be better off without a salesman involved. There's nothing wrong with asking them if they're sending a salesman or an exterminator, we get asked all the time. Even if termite treatment were applied today, it might well take 3 months to take effect.
Local guys have to look the customer in the eye.
You have plenty of time to get the right guy, you're probably going to be dealing with him in the future. You'll probably never see the salesman again. My two cents. Get back with any questions.