Gynecologist ??

This is probably the wrong room sorry but I don't know what other room to put it in. I don't remember who told me but someone said that we should start making appointments with a gynecologist when we start having sex. I've been having sex for a while, but i haven't visited a gynecologist yet. Is it necessary ?? If so how do I ask my mom to make me an appointment ? I'm 16 so she'd be upset if i told her I was sexually active and that's why i want to make an appointment. Do i just tell her and ask her to take me to the gynecologist or do i wait?