Hi. It's not the "age" of the person that matters as much as the insight the person has.
If you are as comfortable as you can get with your identity, AND are able to withstand the potential disapproval of people who are important to you, then you are headed in the direction of being able to be responsible for yourself.
Unfortunately, all too often opening the discussion with loved ones does not go as we want or need it too. I would strongly recommend that you be in a position to deal with any disapproval that may come your way (from important people in your life).
If there is any chance that you would be put in danger by letting your family know your thoughts, then I would recommend you wait until you can be safe before launching into that sort of disclosure.
Take care now and take it one step, one day at a time.