GO DM MODS OF YOUR FAVORITE SUBREDDITS AND POLITELY ASK ABOUT MIGRATION!
Please don't do this. I'm a moderator of a sub (won't say which one). From a personal standpoint I'm happy to use both platforms. Vilify me if you will. But I do not want to see messages from users asking if we're going to migrate. That's pestering and it won't go well if that particular subreddit isn't into it.