my flight is scheduled to land in 07.07 morning at Beijing Capital airport.

Will you head for Erenhot? As I know, the earliest bus departing from BJ is at 17:00. You may need to take the long distance bus from Lizeqiao Long-Distance Bus Station. The duration is about 9 hours. From the airport, you may take airport shuttle bus Xidan Line to Xizhimenqiao South Bus Stop first. Then you may take bus no.691 to Lizeqiao Bus Stop. Upon arrival, you may walk about 500 meters to Lizeqiao Long-Distance Bus Station and take a coach to Erenhot directly. This coach may probably stop at Erlian International Bus Station. You may consult the staff when you buy the ticket.