I'd get used to the 8:15 pm home game start times if I were you.
And that's not necessarily a bad thing for BYU football. One of the big reasons BYU is so valuable to ESPN/FOX/whoever broadcasts games is there are way less good games in the country (especially in western time zones) at night. Home games in the middle of the day and afternoon wouldn't compete well against national broadcasts of Notre Dame, Clemson, Alabama, Oklahoma, Texas, etc games throughout the morning and afternoon anyway. I can see why it might not be ideal for East coast cougar fans, but in the Big 12 most of our away games will be day/afternoon games.
It will be a huge financial benefit to the BIG 12 and its future television contract negotiations to have ability to compete with (and usually beat the Pac) for ratings during the night game time slot, something they've never had before. And as far as benefitting BYU, every Saturday night we will maximize our exposure (relatively) being the "only game on TV worth watching" at that time, with only crappy MWC games or games on the Pac12 network that nobody can watch as competition.
The late home games are here to stay. I'm starting to really like football at night though. The team and fans look great under the lights on TV. [Note: I'm in California so they seem quite as "late" for us here.]