The earliest you can get to the West Coast USA.
Since Ethiopian introduced their direct line from LA to Dublin this year, for the first time it's now possible to get to the US west coast in time for an almost full day of work. Their plane leaves DUB at 6.15AM and arrives at 8.50AM at LAX. Plenty of time to get to a job or have a day meeting. A little tip for those who might need it.
I wish it was possible to go the other way and not lose a day, but alas, it is not. I very often in my line of work get last minute calls where they ask "can you be in London tomorrow morning for a job?", and even though they might call me early in the morning LA time, there is no way for me to physically get there with the time difference lost because no airline leaves early enough. If there was a morning flight leaving LAX, I could get to London in time, but they all leave in the afternoon.
But again, Ethiopian also leaves the latest from LAX, so as long as they call you the evening before, you can get a late plane out and not lose yet another day. Leaves at 11.45PM, so you're in DUB by 5.45PM the day after. Enough time to get you where you need in Europe for the day after.
Flew the trip in June on their nice 787, and they did a good job.