I have a United Airlines domestic flight from O'Hare airport at 8pm (Thursday in September if it matters) and I want to know how early I need to arrive. I need to check luggage and also I think with Basic Economy ticket I can't check in online. Is two hours enough or should I arrive three hours before the flight?
Two hours is sufficient. I've always done two hours for domestic and maybe two and half for international.
It's personal preference you need to think about the time of your flight, the day of your flight. It may be leaving off time so it would be busy but I recommend you at least have 1 hour and 45 mins of spare time and get to the airport 3 hours before your flight