“I have started meditating on the mantras that you have provided. Which mantra I should focus to start with? Or how do I go about it? Is it allright if I focus all mantras one by one in repetition in my mind?”
You are free to experiment with it the way you feel inspired to.
Put it this way: the energy field you connect with is intelligent and feels your intention.
In other terms, you will get it right no matter how you use these mantras.
Trust your instinct and do what YOU feel is right for you. Trust yourself and follow your instinct
Again, you can’t get it wrong 😉
To your Yoga!