Honestly, it will probably be EASIER for you to travel on the evening of 12/24 than that of 12/23.

7 PM on Christmas Eve is too late for many holiday travelers.

My personal experience on Christmas Eve/Christmas Day (and we're talking 10+ years of traveling on one of those two days) is:

Christmas Eve - Zoo in the morning, dying down by the evening.
Christmas Day - Dead dead dead (unless you're heading to Orlando - heaven help you then).

Disclaimer: I usually am flying into MSP, an airport almost completely staffed by Somali immigrants. So Christmas is just another day for them.