Well, in Paris, they did it progressively. I first noticed it last year because they changed some dates without any announcement in the middle of the season (there is a schedule of sales dates -internet, phone and box office- per show published at the beginning of each season)
The new direction seems to be advertising they have chosen to publish early casting (Millepied himself but also the deputy director of the Opera have tweeted in that sense). We will see if they keep going on, at least for the traditional ballets of the repertoire: It seems trickier with contemporary repertoire and when choreographers are still alive. Rain casting is not up yet and Première is October 21st. But I don't think there is any Etoile dancing this ballet, it might be of importance.