To Baoding, I wouldn't think that buses are more frequent than what's shown (above link matches what's on the en.bcia airport website, but who knows if it's completely current?). If the 16:10 bus is accurate, you won't make a 19:00 dinner. You'd need to leave around 15:00 and even if there was a bus, likely you wouldn't be through the incoming arrival process until after that. I'd make Plan B your Plan A, and get to Beijing West forthwhip and take the next G train out. Take a best guess on timing and book ahead if you want to be assured of a seat. Journey is short enough that even a standing ticket would be workable.