Am arriving 2.40pm at Beijing Capital Airport T3.

And been reading lots about immigration in airport arrival.

May I know how much time I should set aside to clear immigration/customs, grab luggage exit the airport and make my way (by taxi) to the South Train Station to catch train to Jinan? I was planning to book the 5.45pm train (3 hours after arrival at the airport), or I should consider the 7pm train instead?

Thank you.