This article goes into the Year Three/Year Five issue a bit: "The ONLY way to have Robin debut in Year Three is to basically chisel the entirety of the yearlong Dark Victory series into mere weeks."
Apparently the Robin/JLA thing is a contentious issue, though. This Zero Hour timeline puts Robin's debut after the JLA's, but I don't know if DC stuck to that.
My reasoning for before is it makes more sense for Robin and the JL to debut when his “early years” end. But Robin has to debut before the JL due to his appearance in Dark Victory.