Many people think "fetish" means "perversion," something disgusting and repulsive.
By all means, on a first date, compliment the woman's hair. If she responds well to that, try to find an opportunity to casually stroke her hair. If that goes well, run your fingers through her hair. Many women enjoy that, even if they don't regard it as a sexual thing. Don't neglect other parts of her body.
Maybe not on a first date, but many women enjoy having their hair brushed, even if they don't regard that as a sexual thing, either. If you get to the point of showering together, volunteer to shampoo her hair, another thing that many women enjoy.
If you get close to having sex, tell her that her hair turns you on. Don't make a big deal out of it. Tell her about her other body parts that turn you on, even if not all of them really turn you on all that much.
Be sure to kiss her neck, especially the nape. That will get you pleasantly close to her hair.
More importantly, find out what turns HER on or off. You may be surprised in either a good or bad way.
Be eager to go down on her, especially if she is having her period. If you are willing to do that, she might be willing to get cum in her hair.