You become a member of the captains circle on your 2nd cruise with Princess when you get a gold card on your first cruise the colour of your card is blue. Hope this answers your question.
I assume you are talking of the Princess Cruise Loyalty Programme, which recently claimed its seven millionth member. Try this website http://www.travelmole.com/stories/1123691.php
Their top member has accumulated 10 years at sea. Thats nearly catching up with me and I did 30 years in the Royal Navy.