When will I notice real benefits of daily mantra practice for chronic anxiety?

I am Kunal Jain and was born in Hyderabad at 5:05 AM on 6th May 1998. For years I have been dealing with severe anxiety and eventually, I decided to start chanting “Om Namah Shivaya” everyday. But as an impatient person, I want to experience the benefits quickly. I would like to learn the exact duration that one has to practice the mantra before it actually alleviates the anxiety, the mistakes that one may make and the ways to be consistent with the practice.