Question regarding GS interception when approach mode armed

[WhySoTough]

So your FAF, where the GS starts to come alive and you descend with the glide is for example 2000 feet.
If you were at 4000 feet with your approach mode armed, I believe it will intercept the localizer, but will it also descend down to your FAF and further with the glide, or do you have to descend to 2000 feet for the GS to become active and descend with the glide?

Also, is there a certain altitude with your approach mode armed for the localizer to start intercepting?

Thanks!