Just do it! Time and tide wait for no man/woman. My first experience also like you, so kancheong as if this is my first nude public appearance in front of the Tokyo crowd. But once I stepped inside the changing room, before the pools, then I realized it's all my imagination that any men would be interested in my body or stare at my out of shape body parts. No one reacted excitedly when I entered the room, no one side eyed me, nothing happened! One obasan casually sweeping the floor and tidying stuffs while all the naked men leisurely walking around. A few kids teasing one another. One young girl naked and waiting for her dad to undress. After this one time, the rest is history.