L.K.
You could go to nearby park. You could go to McDonalds. You could do it at a friend's or relative's house. You could even have it in your home and make the boxes part of the adventure. Kids love playing in and around boxes, and four years olds aren't judgemental. My daughter is turning five this month, and she's talked about her birthday almost every day since she turned four! Keep it simple so it won't cause you so much stress.