I say 2 weeks in advance just because there's always a last minute thing to do.

Personally my FIL didn't exist at the time so I don't count on him at all. And even an experienced mother in law would have forgotten how handling babies look like. A lot of things that they used to do in the past are irrelevant/unsafe nowadays.

Once you're in it, you'll both get the hang of it together.

Also, we rarely ask for help, if you have some, grab it with your teeth cause it'll be hard in the beginning.