I'm glad that this is part of our history, and I'm not trying to start a fight, but I feel like T should come first. L, G, and B are all (originally) sexualities. Gender identities only get 1, T.
There's a beautiful reason why L is first in LGBT. During the AIDS crisis when most people turned their back on gay men, lesbians stepped up to care for them, donate blood and help in any way they could. After this it was decided that GLBT would become LGBT and it has stayed the same ever since.