I didn't know about it, but as it turns out I did something a little similar to coming out on the 12th!
I went and visited my grandparents, whom I hadn't seen in person in... oooh... about 3 years. Maybe more. We were close, I spend every second weekend there as a kid. But when I was 17 I moved a long way away, and didn't get to see them as often. Then later, further away and saw them less.
I was sent down their way on business, so I thought once afternoon after work I'd call in. So I drive down there, go to the place where I am staying, and the owners aren't home! I kinda needed the bathroom, and the only other people I knew in that town were... the grandparents. So I took the opportunity to visit them, albeit unannounced (I did, of course intend to call first).
I knock on the door, and my Nanna answers. She looks at me blankly, as in "Can I help you?". I say to her "Hi! I really need to use your bathroom

". She looked at me, confused as hell. So I added "It's been a really long drive

". About 3, maybe 4 seconds went by and her jaw dropped. Once she collected it from the floor, she tentatively asked "<female name>.... is that you?".
She isn't losing her marbles, I just underestimated how different I looked

.
Turns out the only thing that made her twig was 1. My car was parked out the front, and I'd put photos of it on facebook, 2. I was in my work uniform, and my job has been big family news, and 3. I look like a younger clone of my estranged for good reason, good for nothing biological father.
The whole family already knew about my transition, and there's a 6 month old photo of me on facebook (at 2 weeks on T). Guess I've changed more since then than I thought!

We all then had a great laugh about that doorstep exchange over a nice cup of tea, and all was well

.