There are only 2 OEMs that have surpassed that milestone, both happening this year:
Tesla got there around last April;
The Renault-Nissan Alliance reached the 1 million mark a month later, in May.
And who will be next?
Well, BYD and the VW Group are the main candidates, but both shouldn't be able to get there this year, but expect at least one of them to get there by Q1 2021.