It is fine to take a shower within 24 hours after your LASIK procedure. But you should not let the soap or shampoo get into your eyes at least one week after the surgery when you take a shower during the healing process. When you wash your hair while taking a shower, you should turn your back to the shower so that the shampoo can be washed down your back not your face, which can avoid the soap or shampoo getting into your eyes to cause any discomfort.
In order to avoid dirty water into your eyes, you'd better not take shower or wash head within 3 days after lasik surgery. That because it is likely get your eyes infections. Of course, you can take shower or wash head if you really want, you must be very careful and do everything you could to shield your eyes from waters coming your eyes. For example, you can keep your face away from water and close your eyes when you take shower, and clean your face with a wet soft cloth.