Ok MIA experts...I need some advice please

Mi suegra (mother-in-law) is going to meet us at Miami International next week. She is arriving on Mexicana Airlines at 7 p.m. from MEX while we are arriving a couple of hours later on UA from SFO.

I'm guessing her Mexicana flight will arrive at Terminal "E" and she'll clear immigration and customs there. Any idea what kind of lines she can expect in the early evening?

So after she clears MIA's immigration and customs, where would be an easy-to-find spot at MIA Terminal "F" for her to wait for our later arrival on United?

Thanks all!