Started birth control 3 days before period?

I'm supposed to get my period within the next 3 days, but I've always been super irregular up until about 2 cycles ago. I have some early symptoms of my period: like bloating, and moodiness, so I think I might get it regularly. But my mom
suggested I start my birth control now, so I took the first pill in the pack..I'm wondering how this will affect my period? Is it really bad that I started so close to my period? I've never been on birth control before so I'm new to this..
Thanks in advance for the help!