I did a three point 150nm dual, and was signed off for solo CC. My first solo CC was a 50nm trip to an airport I'd never been too. After that I did the long three point which was right at 160nm, and a 50 right before the check ride. Every CC was to an airport I'd never been too, and one was GSO in class C airspace. Its all about what you feel comfortable with, and what your CFI thinks of your progress.