On my early February travel that included Flight: UA917 Aircraft: Boeing 777-300ER Fare Class: United Economy (HN) - (I class requested), no I class came available prior to T-24, but at check-in (~T-10; could not check-in online due to having to show proof of onward travel at airport for one way ticket) I was placed at #2 , ahead of about 10 that were on the upgrade standby list by this time. So the automatic transfer worked as advertised and it appears that I was placed ahead of most if not all "paid economy requesting upgrade" passengers. I moved slightly up and down the list in the last hour before boarding, but eventually was cleared to biz!