• very high level of success in any given field (especially in the entertainment business, e.g. "the actor dreamed of making it to the big time.")
• the big time is used to refer to the highest level of an activity or career where you achieve the greatest amount of success, fame, or importance; an informal expression.
big time operator
• person with a lot of influence; one who is active in a central way (in a project); activist; person who is actively involved in many different causes (commercial or otherwise)