From what I've seen, I think that you'll find that, for Mexico, in process to PPR timing is not consistent in terms of x weeks or so.
The reason I mention the Police Certificate to PPR timing is that I've noticed that year after year there seems to be 'batches' where everyone who has received a PGR request over a few months gets the PPR over a couple weeks. The exception are the cases where they ask for additional proof of relationship or where some added twist kicks the applications out of the 'batch processing' into their own timing so that the other elements can be addressed.
It will be interesting to see what the actual statistics indicate if you collect them. trackit used to have them, I don't know if they still do.
Don't worry about asking any question - it's normal to try to dissect it in order to better predict. When you get frustrated, redirect some of the energy into lists of places to see, things to do when she arrives and into prepping your home (does she have closet and drawer space already?)
Or, ensure she does her B4, gets driver's license history, etc so you don't have anything left to do when she does get the PPR.