I'm coming in from Keflavik (KEF) with WOW at 5:30pm (Terminal B), and there is one later flight to DFW with United at 8:59pm. (Terminal C), so I have to go through immigration and then go to the check-in counters from United and check-in my bags again.
I'm traveling with two older children, so I usually can't do any drop-off or curbside check-ins, we have to go to the counter. We are US citizens though. Do I have a reasonable chance to get the 8:59pm flight?