Maxperson
Morkus from Orkus
The writing you quoted actually tells us, and then proceeds to contradict itself.How do they know they're afflicted? They need to know before they can choose to resist or embrace.
"However, when the full moon rises, the curse becomes too strong to resist, transforming the individual into its beast form-or into a horrible hybrid form that combines animal and humanoid traits. When the moon wanes, the beast within can be controlled once again."
That tells us pretty clearly that you can feel it the entire time, but can resist/control it outside of the full moon. If you choose not to resist, you become the alignment of the werecreature while in humanoid form as well.
Then we also have.
"Especially if the cursed creature is unaware of its condition..."
That pretty clearly tells us that the creature might not know, despite resisting and controlling the curse outside of the full moon.

It says that they can once they embrace the curse.What about changing before the full moon?
"Some individuals see little point in fighting the curse and accept what they are. With time and experience, they learn to master their shapechanging ability and can assume beast form or hybrid form at will."
It says that they do, but also might be unaware of the curse that they are resisting, whatever that looks like.Can they resist it before then when the moon is full, or is it just the full moon?

One or three, depending on which school you ascribe to. But yeah, new DMs might not know that. It's pretty easy for them to rule, though. One or three are both good answers, and they'll say one of those.How many days is that?