I think it depends on how attached you are to him. Will you be devastated if he responds poorly? Also, do you have other options--other therapists you can see--if he responds poorly? You mentioned you live in a rural area so I'm wondering how many therapists there are...

I really think you deserve a therapist who accepts your sexuality. So if you're not too attached, I'd say it's better to find out sooner rather than later. But if you're very attached and would be devastated if he responds poorly, or if there aren't other therapists you could see in your area, then maybe proceed with caution as some others have suggested.

Just remember, if he responds poorly, thinks it's a sin or a disorder, it's his problem, not yours. He should find a time machine if he insists on living in the 1950s.