I realised being able to answer this question well depended on my mood and how confident I felt. If I rehearsed answering my name over and over before meeting new people I was guaranteed to block because I felt insecure and afraid. If someone asked me the question out of the blue while I was already in a chill mood then I would be able to answer it with no problems. One thing that helps is to say "MMmy name is x" instead of just saying your name" and also looking the other person in the eye will encourage you to get the word out quicker.