It’s quite appropriate to go now. You don’t need to make an appointment. You can take the Mubus direct train to get there directly. There is also a tour guide on the bus to help you book tickets, which saves you worry and effort.
There are not many people now, you can scan the QR code to book tickets at any time, or go to the window to buy tickets, the fare is 50 yuan. Some ticket-free policies, half-ticket for those over 60 years old, and free tickets for the Beijing Senior Citizen Card.