I was waitlisted for business on economy award ticket (HEL-BKK), asked about it at T-5-ish days on whatsapp and they said there are still empty seats, "looks good". Got the email and new ticket at T-37 hours. This had PE upgrade availability when I was booking so upgraded to there instantly, but got some vouchers expiring this summer so I asked on whatsapp to waitlist on business as well (about month before takeoff). Good stuff!