FWIW Icelandair charges the same for seats before and after checkin. So if you are willing to roll the dice, you can always see what you get for free and then pay if you don't like it. Even on full flights you could probably set an EF seat alert and something will open before departure. Of course this should not apply if you should be getting an advance seat for free.

OP I think it will be more than 2 weeks...I have been waiting over 2 weeks already from Icelandair for a simple delay acknowledgement paper for travel insurance