I think our son was 2 or 3 when we started. The first night in a tent was simply in our backyard. That way, if there would have been any problems, we could just move inside and try again some other time. If that is not an option, I would go to the nearest campground (hopefully no more than an hour away). Don't go for scenic or whatever. The idea is just to get them used to sleeping in a tent at a location where if everything fails you can go home in the middle of the night and come back in the morning to pick up your tent and gear.