One question is whether this is a good career move. A lot depends on your relationship to the colleagues and the customs at your company.

If you're thinking of using a RUC, you could call and ask about upgrade availability. If OP/RP space isn't available now on your flights, there might not be much advantage in splitting the PNR and applying the RUC until several hours before departure, in time for gate upgrades (and to check that the RUC has been coded correctly). OTOH, you could split the PNR just before T-6 and hope that your upgrade clears at the DM/PM window as a free elite upgrade.

In either scenario, requesting the upgrade earlier might move you up the priority list slightly, but perhaps not enough to matter.