Yes, it may be delayed prior to your boarding too! And you can not count on the "scheduled" arrival time in DEN as an absolute either. (Especially if the train is "scheduuled" to arrive about 8 PM, and your flight from DIA is at 11 PM. )

I just read a column in R&R magazine where the CZ "a few years ago" was scheduled to arrive DEN about 8 PM - but did not arrive (due to UP conditions) until 7 AM the following morning!

But YMMV (thankfully).