Time from Dongzhimen to Yangjiayuan by 916 express

Hello,
I intend to travel to Xizhazi Village this coming weekend using the bus 916 express to Yangjiayuan and then the bus from Yujiayuan Coach Station to Xizhazi Village. How long does it take for the 916 express to reach Yangjiayuan from Dongzhimen? What time do you recommend that we catch the 916 express at Dongzhimen to get the bus to Xizhazi which leaves at 16:30 from Yujiayuan Coach Station?

Thank you for your help!