I am right now waiting for M->Y upgrade to clear on CPH-NRT tomorrow (cost was €199). There is availablity in all cabins on this flight but I hope SAS wants the extra added revenue for the upgrade even if they don't need to clear space in M. I am wondering whether I will kill the chance of it clearing if I check in online? What is the closest time to departure that an optiontown upgrade has been cleared for those who have tried it here?