Wheelchair availability from 1200hrs to 0500hrs (next morning)

my husband requires wheelchair assistance as he cannot walk long distances. we arrive Beijing airport wed 21sep at around 1pm from the kidney hospital and our connecting flight is KA905 to Hong Kong on Thursday 22sep depart at 0800hrs. We would like to wait around the airport preferably at Terminal 3 as this is where we checkin for our flight to hong kong. Is it okay if we wait around? How can we arrange for wheelchair and for someone to assist us push the wheelchair to the checkin counter ?