A large part of what we do in the martial art is concerned with the practice of mindfulness and commitment to act. This is expressed through every act we engage with within the training space, and should be reflected in all aspects of your lives. A very small outward sign of this is manifested in being clear with your sensei when you have commitments that take you away from your regular training habits, and always trying to be punctual to class so that it can commence on time.
Despite best intentions, at times you will be caught up and inevitably run late. The question then becomes how to integrate yourself into the class without causing too much disruption.
For most Japanese martial arts, the protocol is to get yourself dressed and equipment prepared as quickly as possible, position yourself in the far corner/low seat of the training area, and wait for acknowledgement by the sensei to then enter the training space and slot in with what the rest of the class are doing. This is often done when there is a small pause between specific exercises so as not to interrupt the flow of the class. Usually this is done in the seiza kneeling posture, unless you are physically unable to do so. Before entering the training space, you perform rei (bow) to both the sensei and to shomen, then take your place at the nearest available opening — not necessarily where you might "usually" position yourself due to considerations of rank or habit. Again, it is about minimising the disruption to the class.
Sitting in seiza till you are invited to join provides you with the opportunity to engage with zazen — the meditative aspect of our training that mentally prepares you for the session ahead. However, the question often asked is in regard to the physical aspect of preparation for a class. This is because when folk do arrive late, they usually do so part way through jumbi-undo (the physical warm up). Generally it is assumed that you do a brief, relevant warm up before you sit in seiza. Obviously this will depend on the activity you are about to commence.
In Jujutsu we will be instituting a new protocol from this week for completing the physical part of the warm up should you find yourself late. We will be setting up the two "spare" tatami as a warm-up zone. You will be expected to do ten "bridge" exercises, ten "shrimp" exercises, and ten forward rolls (5 right and 5 left handed) before taking position in seiza. If there are a few of you running late, you will have to wait for the previous person to finish their set of exercises before starting yours. After this, please follow the protocol set out above, and wait to be invited to join in the class.
I hope that this makes the procedure more clear. I will be reminding everyone over the next few weeks so that it becomes embedded in what you do without having to think too long about it. As always, if you have any questions, please feel free to ask!