The best thing you can do is talk about your future aspirations and dreams. Trust me, no girl wants to hear a dude say he can't wait to sit at a desk for 45 years then retire and play golf and watch tv. Even non-mustachians know that sounds pathetic. Talk about your big ideas, the thing that keeps you going, the reason you can't wait to FIRE. And then when she asks how you're going to make it happen, tell her you have a master plan and wink. If she likes you and thinks your dreams sound like something she could get behind, she'll ask more questions. If she thinks you're crazy, you just dodged a bullet. Good luck.
Perfect. I'd go with this. Under no circumstances would I mention the R word (Retired). Their perception of that word, has no bearing on what it means for you, and it can scare them off. If you have to put a word to it, after you've talked about your aspirations and given her the wink, say "Financially Independent."
If she needs an explanation of how that works, keep it simple and just say "savings". People understand savings. Don't mention investments, stocks, or safe-withdrawal-rates. I find that complicates the conversation, and makes some people (especially if you don't know them well) think you're running some kind of scheme. When explaining it, I take a page out of Arebelspy's book and explain it like this:
"If you save 10% of your paycheck a year, and spend 90%, every 9 years you'll be able to take a year off. Makes sense right? Now what if you save 20% of your paycheck, and spend 80%? Now every 4 years you can take a year off. A HUGE jump!
Now let's do something crazy...if you can manage to save 50% of your paycheck, you can take every other year off. (I give them some time to think about that, and maybe make small talk in between about how that could be easily attainable by living off one partner's salary and saving the other).
(Then I drop the bomb) Me personally, I'm saving 80% of my paycheck. So for every 1 year I work, I can take 4 years off. But I'm not actually taking the years off yet. I'm putting in all my work up-front, so after a few years of this, I'll never have to work again."
In a dating situation, I'd just say "I plan on saving 80%", so they don't start thinking I'm rich.
If she starts going down the path of calling you a lazy bum, mention that "Financial Independence isn't the end of work, it's the end of
mandatory work, and start repeating your aspirations and the things you'll be able to accomplish once you're free of the daily grind. If she still seems resistant, you're in trouble.