Your check-in time should be 90 minutes prior to your flight.
Most airlines CLOSE THEIR COUNTERS TO PASSENGER CHECK-IN 30-60 MINUTES PRIOR TO FLIGHT TIME. Most airlines also expect passengers to be in the boarding gate area 20 - 30 minutes prior to flight time.
Please be aware of these requirements as you make your plans to come to the airport, and allow yourself enough time to check in and go through the screening area. If your flight is delayed, you should NOT change your originally planned arrival time to the airport. Delayed times can be cancelled or changed.
Most airlines require you to be in the gate area 30 minutes prior to the scheduled flight time, even if the flight gets delayed. Contact your airline for further details. It is always a good idea to double check the status of your flight by checking their website.