I firstly applied for WDL in May 2019, BQ (basic qualification) done in Interpersonal (Hamburg) around mid June, they invited my immediately for the Sim (Passed in August), and then they've shown up now for the interview, after 5 month.
The process could take long time, and, even if it's not written, I have the feeling they prefer people with a good level of German.
Anyway, try every opportunity, apply and go if they invite you, you never can tell.