Lucerne to Chur train to connect with Bernina Exp

I will be coming from Lucerne to Chur on 12 May to connect with the Bernina Express leaving at 8:32 am. The train from Lucerne to Chur via Zurich is to arrive at Chur at 8:22 am. I realize the Bernina Exp and the Zurich train are just across the platform from each other but a 10 minute connection seems too tight. What do you think? Are the only other optons either driving from Lucerne or spending the night of 11 May in Chur? Thank you.

Thanks, Arno,
I thought the earliest train was at 6:10 am. I wasn't using the RailEurope website correctly. I now see that "First Train" does not mean the earliest train available that day but the first train displayed on the screen. Regards, Ted