For Alpha Phi, our timeline is like this. The collegiate girls were pinned as New Members back in April 2008; this includes the women who will graduate before the chapter is installed, so they'll ultimately be AIs. (All of the NMs of the colony as well as the alumnae of our local are allowed to wear Alpha Phi's letters now.) In the fall, more girls will be recruited to the colony, then pinned as NMs. After that occurs, the traditional NM education will begin for everybody, both girls from our old local and the newly recruited girls. Both the collegiate NMs and the local's alumnae will be initiated as the chapter is installed, sometime around March/April 2009. Both collegiates and AIs will be allowed to sign the charter.
For OPhiA, an interest group is formed. They cannot become an official colony until they've met a certain list of requirements, including getting their numbers up. If I recall correctly, the colony phase lasts about a year. Part of the colony process is that the colonists take on their Alpha pledge class before they themselves are initiated, to ensure that they understand how to recruit and maintain the group's numbers. When the chapter is installed, only the original colonists are initiated. Those women may then initiate their first pledge class whenever they see fit. (In OPhiA, no colonists or pledges are allowed to wear our Greek letters; however, they're more than welcome to wear things that say "OPA" or "Omega Phi Alpha" written out.)