It is currently not possible to create a waypoint station or a refueling station where a train waits for X time, because trains ignore the "After time passed" condition unless there are matching load/unload modules or refueling modules.
This appears to make separate refueling stations impossible to create.
See screenshot for an example. I've told trains to wait a ridiculously long time at this station to ensure they get refueled, but they all blast through without stopping.
Further experimentation on another station shows that indeed: if I add a dummy module (a loading module that never contains product) that matches what the train can carry, then the time based condition works, both when used by itself and in combination with a "full" condition.

Quick correction: they don't really "blast through" but, more accurately, they stop and immediately depart.
Screenshot of it happening attached. You can see there's plenty of fuel but the train did not get refueled, despite the "Depart after 1234 days" condition.

