Similar problem for me right now; Jetblue can't find reservation, but then Icelandair says "check in not yet open"... Opens in 23 hours. The FLIGHT LEAVES IN 23 HOURS.
It's like they're off by a day.
And YESTERDAY, around 48 hours before departure, it said to check in...
JetBlue wait time is 147 minutes, and Icelandair is constant-hold, with creepy Icelandic soft rock playing...