8 a.m. to 9 a.m., or 1 p.m. to 2 p.m.
You'll spend less time in the waiting room if you book the first appointment of the morning or the first after lunch, says Patricia Carroll, R.N., author of What Nurses Know and Doctors Don't Have Time to Tell You ($15, amazon.com): "Doctors start fresh in the morning and catch up when the office is 'closed' for lunch." Many lab tests require fasting, so a morning appointment will help you avoid being hungry half the day. If you're seeing a doctor who performs surgery (orthopedist, gynecologist), ask that your appointment not follow her operating time―a recipe for serious delays, says Carroll. Pediatricians' and family-practice offices can get mobbed when work and school let out (5 p.m. to 7 p.m.). And if you leave with a prescription to be filled, try to visit the pharmacy before 3 p.m. on weekdays, when it's least busy―"which also reduces the risk of error," says Carroll.