There is no universal rule that everyone must wait a certain number of hours after a routine flight before getting a massage. If you feel well, have had something to drink and eat, and are not dealing with concerning symptoms, a gentle relaxation session may be reasonable.
Settle first
After landing, give yourself time to collect luggage, reach your hotel and assess how you feel. A rushed appointment immediately after a stressful arrival may be less relaxing than a later session.
Hydrate and eat normally
You do not need a special detox. Normal fluids and a moderate meal or snack are enough for most travelers.
Do not massage unexplained swelling
After long-distance travel, new one-sided leg swelling, significant calf pain, chest pain or breathing difficulty require urgent medical evaluation. Do not assume those symptoms are ordinary travel stiffness.
Keep the first session gentle if you are exhausted
If you slept poorly or feel dehydrated, a very intense session may not be what you want. Communicate how you feel and choose a comfortable pressure.
Related: massage before or after a flight.