Hi Ferguson14!
Sorry it's a late reply.... I got a call about 2-3 weeks after my assessment session. I leave on the 22nd of March so in total it has been just over a month since my assessment to going for Flight Screening and OSB. As Rivercat mentioned, it all depends on how you and the dossier you sent away are ranked against other candidates. I also didn't know this until recently... I believe it was mentioned somewhere in this thread
Best of luck!