Culpepper was announced as directing the first two episodes of the show -- the first woman to do so for a Starfleet series -- earlier this week. Since then, she's been answering fan questions on Twitter. One fan asked if there was a casting call yet for the series. She responded, "It's started."
It’s started.— Hanelle Culpepper (@Hillview798) March 2, 2019
As it stands, Stewart is the only confirmed cast member for the series. However, that should change relatively soon, especially now that we know casting is definitely underway. The reported character breakdowns from earlier in the week revealed seven core characters, though it's likely more will be cast than just them. This also does lend some credence to those earlier reports, as character breakdowns would almost certainly exist for the series at this point.
In a later tweet, Culpepper also confirmed that the series still does not have an official title yet, and that the writers room had been hard at work for some time before she officially joined the series.
Not yet— Hanelle Culpepper (@Hillview798) March 2, 2019
The Picard Star Trek series on CBS All Access is expected to premiere by the end of the year.