I would say, XDMI digital card - 2-3 days. XDMI analog card - 2-3 weeks.
Settling or burn-in time is quite interesting in general. With the linear power supplies I have been building, I've had people who stopped hearing changes after 2-3 weeks. And I had people who were very sensitive and could hear changes after 3 months. Usually they all stopped hearing changes after 4 months.
When I got my Extreme, I kept hearing improvements for an entire year!
From my experience the burn-in time people hear is subjective and depends on several factors (usually a combination of all)
1. How experienced you are as a listener.
2. How resolving your system is.
3. How often you make changes to your system.
(your ears and brain also take time to adjust)
#3 is an interesting one. People who have not made any significant changes for a while (and are experienced listeners with resolving systems) usually can hear changes for much longer. That's understandable as they've had much more time with their initial reference point.
And those who tweak and tinker their systems on daily/weekly basis are mored used to hearing changes from various changes much more frequently and may not have a choice but try to establish a new reference point fairly quickly (so they can move on to other changes and tweaks).
There are also people who are not very sensitive on the burn-in changes or simply don't hear much.
The Olympus makes your system more resolving and you start hearing small changes that were not so obvious before. And usually one doesn't jump on buying an Olympus if the other components are not resolving. So I do expect most people here to hear changes with the XDMI analog card for at least 2-3 weeks (say 500 hours). And I do expect some more sensitive ears to hear improvements over a much longer period.
One thing also worth mentioning is that the Olympus itself will keep improving over a long period of time. We don't have completely burned-in Olympus and what we are hearing initially is not just from swapping the XDMI daughter cards. So it's all kind of a moving target for the first several months. But regardless of that the XDMI analog daughter card needs much more time than the XDMI digital daughter card.
In
@oldmustang case, I don't think his dCS Vivaldi will benefit from more hours on his digital daughter card. But the XDMI analog card will keeping getting better, and so I expect that if he repeats the same tests in 4-5 months, the delta will be even bigger.
Of course both (dCS and XDMI analog) will benefit from the Olympus itself running in / settling over time.