I think it's probably good to wait until you've been out a few years-- get yourself settled with a job and all of the necessities with surviving on your own, and then step back to help out. If, in the meantime you want to stay active-- get active on the *alumni* end. Help with a local alumni association, or if there isn't one-- start one (either officially or unofficially).
It's a great way to help out your chapter by giving your members somewhere to go *after* graduation, rather than the feeling of being "cut loose."
I recommend this because if you're acting as an advisor to folks that were active during your years as an active, that distinct line can get a bit tricky (and you might get some resentment/worry within your chapter that as a very recent alum, you're trying to dictate how the chapter runs).
Plus, I think a few years out of college also helps detach you from any of the obligatory drama that might happen within the chapter... and as an advisor, you'll need to stay somewhat impartial to help them out.