We will be arriving at Milan on flight from Frankfurt, where we will have cleared passport control after having flown to Frankfurt from Philadelphia. Our flight arrives at 10:35AM and we are planning on train to Padova at 1:55PM. Are we allowing enough time to de-plane, pick up bags, clear customs if necessary and get to the Central train station.
If your arrival airport is Linate, there are two buses/hour and the trip takes about 30 minutes. If you arrive at Malpensa, there are two buses/hour operated by one company and three buses/hour operated by anohter company and the trip takes about 50 minutes. In either case, you should be fine. Go here for the details for either airport: www.sea-aeroportimilano.it/en.