While flying up the night before is more ironclad, the timing the OP describes implies a 07:00 or 08:00 departure out of CAN. ATC issues are relatively minor compared to the afternoon flights. Main risk this time of year (November) is possible morning fog at PEK. I still think risk of missing his DL flight is relatively low. However, as OP is flying J and at a relatively non-busy TPAC time, I think he's got a little more room to maneuver with DL in the event of a misconnect.

But OP, if you've got an F ticket on CZ, it should be readily changeable to the evening before, if you decide you'd rather get up to Beijing and stay there overnight to eliminate all risk.