it really should be disclosed right away. Some of the real life problems trans people face is being fetishized. So she trans people want to hide the fact they are trans. Its actually strongly recommended for a trans person to reveal there gender Identity right away because the world is a dangerous place for really anyone in the LGBT+. Also I personally know someone that had a hard time accepting Transgender people because someone he dated hid it from them for so long. He just didn't trust them after what happened. Like it or not this is a deal breaker for a lot of people. And it's better to end things on good terms then to No one likes to be lied to or lead in to a false sense of security and have the rug pulled out from under them. Everyone deserves the right to know what there getting in to.