I am a Reiki healer and certified massage professional. What is the best starting introductory session for my clients so that they see an immediate benefit?

30 minutes of high heat levels at 50-70 C for a patient with good health is the best starting point. It would be great to combine the first session with PEMF therapy (if your mat has it). 

Half an hour of such a trial run is noticeably felt and is usually enough to enjoy the mat. 

But for elderly customers or those with health problems, it could be better to start with a longer 1 to 2 hours of medium heat, 35-40°C, with 2 cycles of PEMF, to get the full benefits. 

It is better to have several days’ rest before repeating the procedure.