It's different from person to person. Sometimes hormones are enough... some can pass as women without makeup or hormones, even. For others, FFS is indeed necessary.
I think I pass as female without makeup, but I know that I didn't at one time... it took me seven or so months to reach that point. However, while passing without makeup is a wonderful milestone and great self-confidence booster, it doesn't really negate the necessity of makeup in daily life. It always helps.
It's hard to know whether you can get to that point before you've been on hormones for a while. And even then... a person's face, or even their physical appearance as a whole is only a part of the picture. The other large part of it is a person's mannerisms, how they carry themselves, how they walk, and most importantly the quality of their voice. It's usually assumed that the mannerisms are correct by default, but that's not always the case.
I don't think the mannerism-and-voice aspect's importance can be overestimated.