Depending on the facilities, you should arrive at least 15 minutes early to your appointment. When entering a spa, you will need to fill out a form. You'll be taken on a tour of the facility and you will need to change into your robe. But honestly a half an hour to 45 minutes early is best because that way you can enjoy everything they have to offer. Many spas have lavish sitting areas where you can enjoy tea or fruit-infused water while listening to soft music.