Early morning engage rev gear car not moving for at 3 mins

Have had the transmission serviced lately, fluid and filter? Most auto manufacturers recommend changing the fluid and filter every 30,000 miles. I guess I would start with that, don't rev the engine while your waiting for it to go into gear. There is a good chance that the reverse clutch is partially engaged and if you rev the engine to try to make it go, you will burn that clutch up for sure. Also, park the car in such a manner that you don't need to use reverse, right away in the morning.