Whether to come out to your tranny date and when is totally up to you, so there is no wrong or the best time to come out. Being a transgender is purely personal. If your relationship developed to some degree, then it might have something to do with the person you are going on a dating with a ladyboy, but that is not the main reason for you to do it and neither need you to explain it to other people.
Some transgender people prefer to come out to all people in their life, while some prefer to keep it as a secret until they feel safe to do so. Some people prefer to do it between. In the past, many transgender people are told by many medical service providers that they should try their best to hide their identity. However, nowadays, more and more people realize that hiding such an important aspect from people might result in serious emotional cost.
Here is some suggestion that might help you decide what is the best action for you.
Let’s assume if you stay silence from the very beginning, what will happen? You might spend more time and energy to worry about when you should reveal such fact and how the other would react. With time passing by, the fear of coming out might grow stronger. The longer you wait, the more scared you are, because the more you will be deemed as a cheater. With regard to this, if you come out as a transgender from the very beginning, you can prevent wasting time with people who cannot accept you or people who may feel being cheated because of this fact. Discussing private things with new people might be difficult, but this is a huge return.
No matter when you decide to come out, you should make sure you are safe. What is pathetic is that the violence for shemales are so common and it is almost impossible to know whether someone has tendency for violence. If you spot any sign, for instance, if he seems to have transphobia or desire for control, you should be very careful. No matter what, make sure you can get help and support when needed whether it is from your friends, family or local police station or government, that is, make sure you come out in public where there are people around.