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 principles regarding direction, sitting mat, and counting rosary are usually not advisable for chanting this Hanuman Mantra. https://www.youtube.com/watch?v=ufkmD95y7fE&t=32s