My guess is that this timeframe varies greatly from county to county from state to state and case to case. Nothing in foster care is standard unfortunately. But 2 months doesn't completely surprise me if there is paperwork and/or legal stuff that needs to be taken care of.
I also would like to note that using the FM as your information resource is not the best indicator of how things are really going. Obviously she would know if M met her APs, but in my experience as a FM they are told as little as possible. Our county didn't plan to tell us that our foster sons were going to be reunified with their birth family until after it was decided in court, which then the boys could have been moved immediately! We heard rumors about it and called a meeting and point blank asked them, so we found out 5 days before court. Communication with FP is horrendous, so just keep that in mind.
But I do think it is worth call the SW to match sure things are still on track and to gently reminder her that you are interested in adopting M if things fall through.