Typically you’ll be lucky to get 2 weeks notice before your start date. I got an LT offer in Jan 2017, submitted all my required documents and then heard nothing. Called repeatedly 3 weeks later and was told my start date would be between March & May. Got a call about 2 weeks before my start date. Then in 2018 when I got my perm offer in Jan(after being laid off in Dec 2017) same thing. Got a call 9 days before my start date. Oh yeah, I was going to work in the same unit. If you got a perm job AND have submitted 100% of required documents, you are good to go. Keep in mind, your not PERM till you pass the FFA. Next 2 FFA’s start Jan 20, 2020. Good luck