1998 Domaine Aux Moines
I would say: not too long. Open it up and try after 20 minutes and it should be just right. I wouldn’t let it go for more than 1 hour. These beasts need some taming, but in this specific case, it’s safe to assume it’s ready for consumption.
Now, the same thing from 1974 would be a completely different story.
Perhaps this is one for the “Audouze method”. Uncork the wine 4 or 5 hours before serving, then re-cork it. That’s it.
It does have the benefit of seeing if the wine is knackered, and also allowing time for any bottle-stinky aromas to disperse. Also, if the wine is initially dumb, it can help opening it up. In a younger wine, you could give it a splashy decant to achieve this, but that is liable to be too much for a very old wine.
Not that yours is a very old wine, but the risk is non-zero, so worth a bit more care.
Anyway, here is the man himself with more details - Audouze method.
I think it’s pretty recent.