The most common carrier of Amazon Packages is UPS and UPS will deliver Amazon and other packages between the hours of 9:00 AM and 7:00 PM although if there's a lot of packages to deliver and it's holiday rush or they just need to get the packages delivered then UPS can deliver as late as 12:00 AM.
There's no guarantee on what time the UPS will deliver your Amazon package. But if the tracking info on UPS website says it's on the truck for delivery today then it will be delivered that day but there's no guaranteed time the package will be delivered.