Several months. The first time it happened it was with the boy that I'm still with after all these years, actually lol. Most of the guys I had been with before were selfish d***heads who didn't care about me, so they had zero % interest in making the sex enjoyable for me. It was all about me making sex enjoyable for them! And when your not enjoying yourself, your not going to orgasm.
For my only time having sex it took her about 30 minutes. It was in the missionary position. Her nails cut into my back which was interesting to say the least. It took me almost two hours to orgasm. She got tired and just had me do her doggy style which I found weird. I hope this helps.
It took me years. I think its just harder for some women. But when you have the right partner and you know you're own body it becomes easier. Sometimes you have to speak up and let your partner know what it is that works for you - then it is much more satisfying.