its approx 13 miles.. so technically doesn't take that long... we have done it at many different times of the day and night and its never taken more than half an hour
17 min door to door with no traffic from the Grand Californian to SNA departures curbside dropoff. Sunday AM there is no typical traffic headed that way.
I would plan on 30 min travel time...and you will likely arrive 10 min early.