There's one odd thing with CX is that they seem to also have a "random" upgrade for MPC members. I remember being a lowly green with about 10k in club miles only and getting op-up'd to J even though economy was not sold out.

Was a random thing I think which somehow gets factored into their booking system.

However, I do believe that if you are going to get op-up'd, the decision to add you to the list will occur before you even get out of bed that day as it generally happens to oversold flights only.

cardenio98