The following message is displayed on the Western Australia government's website:
Invitations for State nomination are usually issued on the third Thursday of each month. This will be brought forward by one week in August due to the transition from visa 489 to 491. Further information regarding the transitional arrangements will be published shortly. Invitations are anticipated to be issued by 9 August 2019.
Source: https://migration.wa.gov.au/services/skilled-migration-western-australia/latest-news