It's trendy these days, for people who go to hatha Yoga classes, to call themselves Yogis.
But in the ancient Tradition of Yoga, the word Yogi referred to someone who had accomplished Yoga and not to a beginner. Swami Veda Bharati has said that "Only those who allow the method (of Yoga) to lead them up to asamprajñāta (the highest samādhi) are true Yogis."
It's human nature. We like to take on airs and believe we are more than we are. But to make progress in Yoga, we have to be honest with ourselves as to our true level. Otherwise we delude ourselves into thinking we've reached the goal when we've barely started the journey.
When, through dispassion and practice over a long time, without breaks, with intensity and devotion, our mind becomes, and remains, clear like crystal, our emotions are always light, pleasant, and joyful, we enter samādhi at will and remain there for extended periods, and we no longer seek fulfillment through experience but from the Divinity within, then we might start wondering whether to call ourselves Yogis.
Until then, it might be best to practice humility and call ourselves students or practitioners of Yoga, and go to the Yogis for guidance and inspiration.