Some people think the Ember Days were last week.
Some people think they are this week.
In the different versions of the Ordo I have the September Ember Days beginning tomorrow.
Usually the Ember Days follow the 3rd Sunday in September. Sunday 20 September was the third Sunday of September. Therefore the Ember Days ought to be this coming Wednesday, Friday and Saturday.
On the other hand, some people say the Ember Days fall on the Wednesday, Friday and Saturday after the Feast of the Exaltation of the Cross. That would make the Ember Days last week.