The twenty-one days starting from your initiation are important. It will be a time of change for you, and you can make sure that change works out as positively as possible by doing focused daily Reiki practice.
The challenge for you is to do some self-treatment every day, for seven days. Whether it’s five minutes or a whole hour, the benefit of self-treatment is only fully realised when it’s done regularly.
Ideally this will be the beginning of a habit that will serve you well into the future.