The FJO will be unmistakable, it will say something like “Congratulations! Your background check process has been successfully completed and you are cleared to attend training.” The onboarding stuff is separate from that and routine post CJO. Guys in my class had a huge range in when they received the FJO, some guys got it months out, some a few days out from class. Prior employers are statutorily allowed 30 days to respond to a PRIA request, and some are better than others at timely replies apparently.