My DS is trans. Stop making a big deal about it. Just correct if you notice in the moment and move on. If you realize afterward, don’t go back and try to correct it. No need to apologize every time. If you were learning to play piano and you stopped to replay a note every time you screwed up, you’d never get through a song.

I promise you’re not the only person in their lives who is slipping up. My DS came out almost a decade ago and I still slip up once in a while when I’m talking him before he transitioned. The hardest thing to get a handle on for me was switching from saying brother instead of sister. During the first year, I had a good handle on his name, decent handle on pronouns, but it took so long for me to stop saying to my daughter, “tell your sister dinner is ready,” or “your sister is staying after school today.” My daughter would usually just say “brother,” but when it happened excessively, she would say “I don’t have a sister, I have a brother.” It was annoying but helpful.

All that is to say all the moms of trans kids I know have similar stories. I’m sure your friend does too. The more you’re around him, the more your brain will recognize him as a boy rather than a trans boy with important to remember pronouns.

A parent of a trans child told me that I should just correct myself and didn't need to apologize.

As long as you’re not doing it maliciously it’s fine, just keep trying

Practice in your head when you think of him. Or try to avoid pronouns entirely so you don’t have to stress about it. But really if you’re trying and self-correct, most people don’t really mind.

When in doubt just use the person's name

Just apologize and say "I swear, I'm trying" and then repeat the sentence with the correct pronoun and then move on.

Friend has a female to male trans teen son. I always generally refer to him as a he, but every time we’re together I slip up at least once and refer to him as she. Any advice?