I would offer up that timing is NOT everything. In some cases, regardless of rather you told early or late, they just don't like it and don't want any part of it. Ever. Sure, some can be coaxed into adapting to it since over time other dimensions develop in the relationship that may weigh in your favor. It's really up to the person you seek acceptance from to decide if they want this in their life or not. It is difficult, then, to change that conviction.
I was one of the lucky. 7 or so years into the marriage my wife suggested it to me. I think she suspected my proclivity, but she simply thought it was cute. She came into the relationship that way and it was an easy sell.
All that to say it is best to try to find someone who accepts from the beginning. Beyond that, degrees of difficulty and heart ache begin.
