Looking to use the procedure outlined in the Caledonia Guide to migrate from GW7 on NW65 to GW8 on OES2/SLES10.

I like the idea of performing the first pass of the PO copy before the outage window to save a bit of time as it states, but is this dependent on having migrated the domain first? Can I perform this first stage PO migration without having to touch the domain/gateways on the live system? Otherwise I have to actually perform the domain & gateway migration before the PO.