The most important thing is to meditate twice a day. The best times to meditate are once in the morning and once in the afternoon or evening.
For most people, I recommend that you meditate soon after waking up—before the never-ending onslaught of emails, texts, phone calls, and daily responsibilities begins. Having said that, Robyn Field, a full-time mom and part-time professional photographer says: “My mom duties start from the second I wake up: making breakfast, preparing lunchboxes, getting everyone dressed and armed with their school work and off to the buses. Suddenly, the house is quiet. I put the phone in airplane mode, slip into my favorite chair, and dive within.”
In other words, find the best times for you and your schedule.
Personally, when I do Tm I usually go into my bed, set the pillow upright, utter my mantra and close my eyes. It is the perfect combination of relaxation, but also keeps you awake. Your Tm setup would really depend on your preferences.