Starting metformin

Deee • Married. 06/03 🤵🏻👰🏽 babygirl : 07/28/18 💕 baby #2 on the way 🤰🏽

I went in to my doctor sus to my last period. I have pcos. My doctor gave me metformin hcl 500mg. Should I wait until I get my period to start or should I just start it whenever?

I have taken home pregnancy test they have came back negative I took a blood test yesterday still waiting for the results. If I were to be pregnant would it be bad for the baby ?