I don't think it really matters where you are coming from. I got an op-up at CDG going to JFK last month, even though I was connecting from MUC (DL flight, AF metal) and still got the op-up arriving late at the gate due to the late connection. This was as a GM on an H fare.

I've also gotten numerous upgrades from AMS to JFK as a GM on a T fare, and have had a colleague travelling with me as a general member on a Y fare get the op-up as well.