Help on temporary custody

[Crockpot]

I've posted this on a couple boards...

My SO got a call from his ex tonight. Her boyfriend recently moved and emptied their joint checking. Her rent check bounced and she's being evicted. She asked my SO to take the kids temporarily. We're willing to do that but would like to make it permanent (didn't tell her that). SO and ex plan to go to the court house tomorrow to file the paperwork for the temporary change.

How does SO take full advantage of this? We want his kids full time. Without bashing, let's just say she's not going to win any mother of the year awards.

How long do the kids need to be with us before the courts would consider letting them stay with us? They live close enough that they can stay in their current schools. But we do live in another district.

Suggestions?