Tourist Bus at 8am(Dongzhimen Station)early enough for 10am TicketService/Shuttle at Simatai G. Wall

Hello,
Is it possible to get tickets for Simatai great wall at the Ticket Service at 10 am when taking the tourist shuttle bus from Bejing at 8 am (Dongzhimen Station)?
If we understand correctly, you can only access the wall at certain time slots and we are not sure if the shuttle bus will arrive in time (at 10 am) to the entrance if it departs at 8 am. According to the Internet, it should take the bus 2 hours to travel from Dongzhimen to Gubei water town.

Thanks in advance for your reply