Figure the first bump will be just 787 FOs in IAH, but if that creates too much of an overstaffing on the 777 in IAH then they will bump off of the 787 and 777 in rounds two and three.
If guys are "volunteering" on the first round they may be senior enough to really create issues for rounds two and three, since they wouldn't be the ones getting bumped off of the 777.