I think she may have had some suspicions with the hat but she is going for a 2nd date and I think as long as the hat was that one time it won't be an issue.
What I'm telling you to do is simply not say nor point out you're bald, just go on the 2nd date without the hat and see how it goes. The fact that you have a 2nd date means she has some interest in you as you were. Let your personality shine, show interest in her (beyond just her looks/body...
And so many bald or not are wearing hair extensions, etc. compared to even 20 years ago. While some (especially younger women) will make a thing about it, what I've learned from some female friends who know about my system (and that I'm a guy in his mid 50s who looks around 40 or so and not...
You have a 2nd thread on this that is a lot clearer. You wore a hat on the first date. OK no big deal it's not like you wore it on EVERY date. Just go without the hat and see how it goes. She probably thought you were wearing it for "style" the first time and now either it will be fine...
Since you only wore the hat on the first date and not every date (which I think would make her wonder anyway) just go without the hat on the 2nd date and see how it goes. I think if she really likes the whole you that will go a lot better than "telling her" which makes far more of an issue of...
It varies with the person. I was basically a "1" with a "white afro" (sometimes nicknamed a "Jewfro") so to speak thru my 20s then just before 30 things changed fast and I was a 4 or 5 by 30 and a "6" a couple of years after that.
I used to do exactly what's being described with swivel mirrors and phone camera every morning back when I was on a concealor routine to make sure I "got it right". I actually for awhile was even trying for a very slight crown balding area to make it look more "realistic" but it was hard to...