[neatoman]

No, the only bit of information we get is that she has "known them for years". I imagine this statement means she met them when they were all still just little kids, her included.

However she met them, it did not involve Baxter Stockman (because he's a child in this and they meet for the first time in his debut episode), Utroms (because we only see a dead one right at the end and in Karai's flashback) or the Foot Clan (because none of them were aware the Foot was still around). I don't like to speculate too much because it could come across as an excuse for bad writing, but I'm guessing their meeting was something like an ET scenario, low conflict cutesy sort of thing.