Most packages through UPS will be delivered between 1:00 PM and 5:00 PM at least that's been my experience.
UPS will deliver packages to businesses first before they deliver to residential places.
Although you should get your package from UPS from 1:00 PM to 5:00 PM UPS sometimes will deliver packages as late as 12:00 AM if they have a lot of packages and have to meet a deadline.
If your package says it's on the truck for delivery today then it will be delivered that day.