Originally Posted by
royial
Can I do the check in few days before and on T-4 to change the seats via the website? Or once I did the check in and choose seats - it's over and it won't let me change the seats in T-4?
I don't want to wait for the check in till 4 hours before the flight

You can check-in at T-48.
And separately as a general wondering... why do we check-in. I do it every time as well. But is there anything really to gain out of doing this?