WHO
  WHAT
  WHERE
  HOW
  WHY
  WHEN
  COST

When?

How long did it take to build New York? California? France? Even given ample funds the first settlement will take decades to construct. No one is building a space settlement today, and there are no immediate prospects for large amounts of money, so the first settlement will be awhile. If Burt Rutan's prediction of affordable orbital tourism in 25 years is correct, however, it's reasonable to expect the first orbital colony to be built within about 50 years.

If the first settlement is designed to build additional settlements, colonization could proceed quite rapidly. The transportation systems will already be in place and a large, experienced workforce will be in orbit.