This is a good question even though the original poster already took the flight. Someday, I may need a wheelchair.

Thinking through the process, my guess is:
No checked bags, boarding pass already printed or on smartphone, TSA PreCheck eligible, able to walk fast, knows the airport layout, no wheelchair needed: arrive at the airport 55 minutes before departure

No checked bags, boarding pass already printed or on smartphone, no TSA PreCheck, able to walk fast, knows the airport layout, no wheelchair needed: arrive at the airport 90-100 minutes before departure, 110-125 minutes during the busiest holiday travel days

No checked bags, no TSA PreCheck, needs wheelchair: wait for wheelchair attendant to come (additional 40 minutes), slower transit time to gate (20 minutes), total time: 2.5 hours ahead of time, 3.25 hours ahead of time during the busiest holiday travel days.

Checked bags, needs wheel chair: add 35 minutes making it 3 hours 5 minutes arrival at airport ahead of flight.

If the person in a wheelchair has to use the toilet often, make adjustments to time needed.