Unless you anticipate extreme cold temperatures while the car is parked, just make sure the traction battery is around 40% to 60% charge. Turn off the car; disconnect/remove anything connected to the OBDII port; close and lock the doors; and double-check to make sure the interior lights go off.
I routinely park at my office or the airport for extended time without concern. The only problem happened one time with the 2011 when I forgot to unplug the Bluetooth device from the OBDII port and left the Android device running Leaf Spy on the passenger seat. That time, I came back to a completely dead 12-volt battery after only 6 days so I had to jump start the Leaf from my office vehicle. The Bluetooth device and Leaf Spy apparently kept the car's computers from going into low power (sleep) mode and prevented periodic charging of the 12-volt battery. The 2011 was parked for as long as 3 weeks and the 2015 has been parked for as long as 4 weeks so far with no noticeable loss of charge from the traction battery.