PCOS & Metformin

Shayne • 🌈💙Ezra 3.17.18💙- 💗Salem 10.1.19💗
Was just diagnosed with PCOS because of high insulin levels, long 35 day cycles, and obesity. I've been on metformin for 4 days and just my period a week early. The first time I've have a 28 day cycle. Does metformin usually cause period regularity? Even though I've only been on it for 4 days?