You have to check-in at SAS, no point even trying on the Virgin website. How much earlier I'd go to ARN would depend on what is happening on Saturday. If you can check-in online, I'd just be there 1 hour before boarding or assuming you have FastTrack even an hour before departure should be ok. If you cannot check-in, and they can't help you on the phone, I would be there as early as possible without ruining my day. Probably I'd give it at least like 3 to 4hrs. Dealing with e-tickets not issued or messed up unusually takes a long time, especially if they are from another airline or OTA. Unpleasant, yes.... I hope it just works our for you in Saturday.
For the two e-ticket numbers, what is are the first three digits? Are they completely different or is it the same with a -some number at the end?