You can attend any time after you take your first degree. You can attend any Lodge meeting that is open and working on the Degree of Masonry that you hold. A Master Mason and a Fellowcraft Mason can always attend a meeting on the lower degree. Lodges in California run business, called Stated Meetings, on the Third Degree. You are an active member as soon as you become a Mason,. You just may not be able to hold offices and do a few things like that.