As that is a Swyama Siddha Hanuman Mantra it does not have being chanted for a fixed number of Mantra Repetitions for having the ability to use it. Distinctive worship and rituals and procedures concerning path, sitting down mat, and counting rosary usually are not recommended for chanting this Hanuman https://www.youtube.com/watch?v=ufkmD95y7fE&t=32s