If you have a relatively cool area, like a basement, that is dark and away from heat sources I think you'll be fine as long as the kit is fairly new. By new I mean manufactured date, not the date you got it. Most kits will have labels with a date code that you can decode to see when it was put together.
I'd avoid freezing it, and if you have the room the refrigerator would probably be good too. But I think a dark, cool area is fine for a recent kit. Others may have experience with storing in a freezer.