The timing must be right for both of you. You may be God's or Goddess' gift to the world and the most sought after prize in town, but no one needs to hear it or wants to hear it. You will have ample opportunity to show how good you are. Don't set yourself up for failure by developing expectations that you know you and your top can never reach. You can learn something about SM and about yourself from everyone into the scene, no matter how experienced or inexperienced they are, or how dominant or submissive they are.
Verbalization is necessary, but at the appropriate time and in the appropriate way.
Your top needs to know basic information about you, such as experiences, fantasies, health concerns, and turn-offs. Don't expect your dominant to be a mind-reader who instinctively knows your needs, wants, and limits. Your cooperation will enhance the scene for both of you. Don't be afraid to share your needs and fantasies. Your dominant expects it.