How early could you check in luggage? I have a flight at 6 am.

You check in 24 hrs before your flight up to 45 minutes before your flight leaves

2 hours

1-2 hours prior to departure.

We had a flight at 6am Sunday and was able to check in at 4am.

1 to 2 hour's.

For a flight that early, I agree with 1 to 2 hrs. I had a boarding time of 11:30am on a Tuesday and was in and out of checked bag and security in 35 minutes with Allegiant.

1 or 2 hours before departure