Just wait at least 3 days since you finished setup your phone to get that great battery life you heard so much about
It says this in Settings - Battery - App power saving: "To save battery power, apps that have not been used for more than 3 days have been set to save power. Apps set to save power may be unable to provide notifications".
Basically this means to wait 3 days after you finished installing and personalizing your apps. After 3 days, all the apps that you didn't use in the last 3 days will be set to save power.
You can install Greenify temporarily to check what apps might keep your device from using Doze. Just go to Greenify and tap on the plus sign. You will see "Running in background" list and "May slow down the device when..." list. Check what apps are in the "Running in background" list and, if possible, uninstall them. After that, you can uninstall Greenify if you want.
Best price in Romania for Galaxy S7 or S7 Edge is found at Orange, neverlocked. I also sighted a good deal at the resealed section on PC Garage (use R2EG5QHA to get 1% discount).