Earliest activation of the promoted global pass?

Hey,

i wanted to buy the promoted global pass from the Save & Donate Sale (16.11.23 - 28.11.23).

I m currently in UK and want to use it here. Now i found, that APC Rail says, that the first possible day to activate this promoted pass is the 28.11.23 (Source: https://www.acprail.com/rail-passes/interrail/ ) but i didnt found any information of that on the interrail site?

https://www.interrail.eu/en/interrail-passes/global-pass

I m asking because i want to active the 2month 10 days pass tomorrow (26.11.23)

Thanks!