Anyone who wishes and has shown themselves to be ready can move onto the Master's degree. You must also be ready to take on the responsibility of being a Reiki Master.
It means that you have had the time to learn to heal yourself and others (this doesn't happen overnight!) and you have developed experience and confidence in what you are doing. Many things can happen during a treatment and it is about being able to cope with different circumstances, different questions and different reactions that you can't learn about just by being told what to do or from reading a book about it.
Once you have lived with Reiki, breathed Reiki and have your own understanding of what Reiki means to you should you consider becoming a Reiki Master. After all, you can't teach something that you don't know or understand yourself.
The third degree will vary amongst Teachers on what will need to be completed. I give students a certificate on completion of their third degree and they must then co-teach a first and second level class with me, finally holding a first degree course on their own.
The main points are:
Be ready in yourself;
Find a teacher that feels right for you to undertake the final degree with;
Take your time over your decision, and;
Go with your instincts.
The choice of where you want to take Reiki is up to you…the most important thing is to just enjoy the journey and to enjoy the journey, you must take time to experience it!