There is no answer to that question. It is not that simplistic. UA, as it should, is much more sophisticated in inventory management. It will depend on the past history load factors, UA's assessment of its ability to sell the premium cabins, ... this will take in account routing, season, day of the week, actual sales to date, ....

BTW, I have already booked and confirmed upgraded multiple SFO-Europe flights for late summer / early fall next year. So you have likely missed the early released R inventory and will need to wait until closer to travel.