FWIW, rideshare prices can change from minute to minute. When you are ready to order one, just check the prices on the various apps right then and pick which one you want. I have found that scheduling them in advance costs more (sometimes significantly so). So I would just request a ride when you are ready to go. For planning purposes, I have taken rideshares from various Disney resorts to MCO at different times of day and the total time (waiting for car plus ride to airport) has varied between 40 and 60 minutes. I got one at Riverside this morning at 5am and it was exactly 41 minutes from the moment I ordered the ride til we were dropped off at the curb at MCO.
With Mears, I usually just book it when I have booked my trip. It can be more or less expensive than rideshare just depending on the size of your group, but I don't think the cost varies if you reserve it now versus closer to your trip date. Also, if you use Mears instead of rideshare, expect to get one hour less sleep