Looks like they passed 30W at about 1900Z, so any time from there forward. Problem with the westbound flights is no LiveATC out of GB, so it's difficult to get their initial HF frequency assignments for Shannon, and they were probably on higher daytime frequencies not covered well, but they should definitely have been with Gander from about 1800Z and New York from 2100Z onward on the lower frequencies. Just have to slug through the archives a half hour at a time... helps if you download them and open them with a wave editor so you can look at a graphical view of the file and pick out the voice transmissions from the noise. Some of the feeds use high RF gain along with strong AGC, which makes it difficult to visually separate the voice from the noise. I prefer to run much lower gain and slower AGC on my HF feeds for that reason... you don't hear them all but what you do hear stands out much better.