If you don't have one, you should order yours asap. They are made to order in Japan by Zen Sankei and are a once-off cost. Zekken pretty much last forever and you can easily transfer them from one set of bogu to another. The only exception is if you need a smaller size for children's bogu. In that case I would order a medium sized one.
Otherwise for adults, order the large size.
Here is the link:
When entering your name, please type first name in sentence case, surname in all caps, e.g. "Jane SMITH" This is to avoid mistakes at the Japan end where family names come first and there can be confusion occasionally about which is which.
This zekken design is required by the AKR for all competitions. If you don't have one like this, you can't compete. And you don't want to be ordering it just before a comp, as theyt ake a while to make and ship.