Based on the outstanding service and field service ribbons; I got my G a month after I joined, and my O a month after that. However, by the time I joined, I've been hanging out with friends (and made new ones) in the Call of Duty division, and became a regular player there for the past several months.
Mak- it is not an obligation to rank up. It's an option for those who wish to take more responsibility upon themselves to help eGO. But the #1 obligation you have is to have fun playing with eGO, enjoy the chance to play with other players who love the same games you do, and hopefully make some friends along the way.