There's a bus called Starfly that goes from LIN to Stazione Centrale with a stop at Lambrate station.

From Lambrate there's a train to Bergamo town.

My flight arrives LIN at 9:55AM. The Starfly leaves every 20 minutes for the 10 minute ride to Lambrate (10:00, 10:20, 10:40, or 11:00 bus). The Lambrate train leaves at 18min after the hour, for the 40 minute trip to Bergamo.

I figure I can easily get the 11:18 train, getting into Bergamo at 11:58, in time for lunch with my friend in Bergamo.

That's my thinking right now. Of course, the best laid plans...