PCOS & Metformin - When did you notice a change in your cycle?

I was diagnosed with PCOS in September and have been on metformin for a month and a half now (started with 500mg/day for the first month, now 1000mg/day). My cycles have been anywhere between 34 and 52 days long and can be pretty awful. I was hoping that after being on metformin for over a month that I would notice at least some difference, and yet there is nothing.

I guess the only difference I've really noticed is that I didn't have a lot of spotting between my periods, mind you I still haven't had a period since starting metformin either. I've still spotted, but it has been so light and only where when I wipe after the bathroom (usually my spotting is as heavy as the average woman's normal period).

So I'm just wondering how long did it take before you started to notice a change in your cycle while treating pcos with metformin?