She has a wierd plastic surgery look to me. Her bone structure suggest she is a mature woman, but the rest doesn't reflect that at all. Her lips feels a bit to puff for her age, she has barely any wrinkles, and her skin is to perfect for that age. Feels like she buttoxed her whole face a bit.
As for the prime comment, I think he just meant woman in their 30s, maybe early 40s. Where they have shaked their childess/teenage physic and appearance (they come over as an adult), but degrading from aging hasn't kicked in much yet. This means if you want a prime year MILF with a legal age daughter, she became pregnant when she was young (like mid twenties at latest).