That should be more than enough time! Remember, you can choose your maintenance provider, and the amount of time required varies based on the aircraft. When you’re scheduling the plane, you’ll see the percentage of required maintenance - you want to keep that as close to 100% as possible.
Additionally, unlike some other airline sim games, passengers do not mind flying in the night. There’s no ORS penalty for flights in the night.
If you search around the forums, there are many excellent startup guides!
Best of luck!