Hi, I've had a busy week, but finally I have time to answer you!
You seem like a really nice person too, so your dear one is lucky too in my opinion.
It's hard for me to judge if it's a good idea for you to try this on your dear one, since I don't know her and I don't know how she might react. But I think it could be a good strategy if it seems like she WANTS to talk, but something is hindering her.
However, if she's evasive and you can see that she really really doesn't want to talk about it, then I'm not sure if it's the best idea. If that's the case then maybe you could ask if she wants to talk about it with someone that's not you. I gave my brother this option too, to give him that choice and to show that I wasn't trying to be nosy, but that I really just wanted to help. In his case he said that if he was going to talk to anyone, he prefered it to be me, but I think that can differ from person to person. I think the important thing is to show that you want to be there for her, and at the same time respect her will. It's tricky, it really is. To push, and yet not push too hard.
It can also be like you say, that she's not ready to open up yet. Then I think the most important thing is to just tell her that WHENEVER she wants to talk, about WHATEVER she wants to talk about, you will always be ready to listen to her. And still love her. And then back off, and let her come on her own. I work like that, I open up when people back off and give me the choice.
My brother had smaller episodes for years, but it didn't seem too serious. I thought I had enough with my own problems and somehow thought he'd snap out of it on his own. Not very flattering, but the truth. But it got worse and worse. I didn't really understand how bad it was until he was in really bad form and started talking about suicide. Then I got scared. From the moment I really set my mind to getting my brother to talk, until he finally began talking it took around 4 months. My badgering questions started around the last 1,5 months. I didn't ask him every day, he would have killed me, lol, but every time I noticed that he was in a bad way (it was very obvious, he would curl up in his bed wispering "I want to die"). I would sit down by him and try to get him to talk. How often he would have his episodes would be different, but I'd say that the general average would be around once a week. The episodes would also last for different amounts of time.
So I don't know if this is a normal timespan, or if it can go faster or slower, I only have this one experience. Like you said I'm sure it's different for every person.
What I do know is that patience is needed, A LOT of patience. An annoyingly big amount really. But it's worth it. Because the patience is one of the keys. It shows that you're not going to give up, and that in itself can help the other one to open up. A surrender of sorts.
I don't know if this answers some of you questions?