I would get a thermometer and check what the actual temps range from. I think it is good that you are preparing for it, I do the same when getting a new animal. I will usually get the terrarium all set and ready to go, and check how the temp/humidity range fluctuates over a couple of days. Zoo Med makes a great little thermometer/hygrometer that will record what the min/max has been for the last 24 hours, around 20 bucks. If it feels chilly to you however, it might need some heating source. Just remember to leave a temperature gradient in the tank in case it gets too warm or cold on one side the gecko will still be able to remain comfortable. Good luck, have fun.