Foster baby #2

We are finally close to finalizing the adoption of our FS. Yayy! However, our excitement was short lived when we found out the the bio gave birth two weeks ago. We were contacted by our case worker to see if we would be willing to take on this child as well. Of course we said yes. But now the baby has been placed with another foster family so that the mother can have a chance to visit, 3x a week (we live about 2 hours away from the bio). Our case worker and the child's lawyer have both confirmed that we would be the permanent placement when the time comes. I know DHS has to give the mother a chance to get herself straightened out but this is her 4th child and she is deep into her addiction. I'm not saying it's impossible for her to reunite with this baby but her track record isn't very promising. I want to be prepared for whatever comes our way. Has this happened to anyone else? How long did it take for the baby to be placed with you?