Hello! I'm sorry you ran into an inconvenience, I'll do my best to help you.
Based on your message, I think you are on day one of the game, is that possible? If so, on the first day the day/night system is disabled, so take your time exploring the academy.
If your quest must be done during lunch time, then you should not go to the dining room, but to the cafeteria, which is in the East Yard, in the northern part of the map. If you have to go to the Dining Room, it's in the Main Building F1, to the west of the map.
Lunch time: 10:30am - 11:30am - Cafeteria.
Eat time: 14:00 - 15:00 - Dining Room.
Thanks for your suggestion to make a mini map. Unfortunately, I currently don't know how to add one to the game. So instead, in your inventory you can access your main quests and the game tells you where to go. Then it's a matter of memorizing the locations of the academy. I understand that this is much worse than a mini map, but the game is still in development. When I can create a map much easier to consult or add a mini map, I will include it in the game. I'm so sorry for the trouble!
I hope my explanation has helped you. If not, please tell me exactly what mission you're on and I'll tell you exactly what to do.
If you have any other doubts, questions or suggestions, please feel free to ask me!