I shouldn't have used "real time," but rather, whenever the servers get updated with account activity, which can be fairly quickly (shown under the Friends tag like "2 minutes ago"). I was testing by having both main and alt accounts playing at the same time, with main account (as a friend) queued up in the Support Eidolons list of my alt account. I played around with changing the main eidolons in the different parties on my main, and simply backed out of the quest queue and then re-entered on alt. Main friend is still a support option (since I never chose it for a stage), however, the eidolons in the given elements were changing.