OK. When did you know that you are a boy? Serious question. You might not have stood up and declared "I am a boy" to the world, but you sought out male friends to play with. You played boy games. You talked about sports, TV programs, etc. that other boys do. You maybe even looked up to your father and wanted to be just like him. You might find that you started doing these things quite young, perhaps three or four.
Now lets say that you have your boy body, but at an early age gravitated towards the girls. Everything that they talked about seemed more interesting to you than the boys. You liked the games they played, the clothes they wear and the things that they do. Boys, you just don't get. You might not stand up and say "I am a girl" but you will know that you don't fit in with the boys, but you prefer the girls. You might discover you were meant to be a girl quite early, or you might have trouble joining the dots until a bit later.
Transition to transgender? Nope. Transition and transgender share the word trans. Think transport, or similar words. They are about moving. So you start as a boy, but the end destination will be girl. So transition is the state in between while you are moving from one state to another.
So lets say that you are 5 and declare that you should be a girl. OK. Putting on a dress does not really effect anything, other than how you present yourself to the world and how people treat you. This is a good time to seek counseling. Having the advice of a medical professional is a good step. The difficulty comes with puberty. So the best thing that you can do is to stop puberty until the child is old enough to understand a bit more about what is involved. T blockers are a great way of taking the pressure off. Delay puberty. In this manner, if the boy decides to stay a boy, just stop taking the Spiro. Puberty restarts where it left off. No harm no foul.
In most countries, although T blockers can be taken early on, hormones are not on the table until the age of 16 and surgery would not be an option until 18. This is UK, but I would imagine a similar scenario for the US.
You might find these useful:
https://www.gmc-uk.org/guidance/28851.asp
https://uktrans.info/attachments/article/5/trasngender_booklet_low%20res.pdf
https://www.england.nhs.uk/wp-content/uploads/2017/04/gender-development-service-children-adolescents.pdf
https://www.wpath.org/
http://www.mermaidsuk.org.uk/
Luck