The ideal time is about 3-5 days before your event. That gives your skin enough time to recover from any minor temporary purging (some people get tiny whiteheads if their skin is very congested) and allows the full glow to emerge. The day after, your skin is usually hydrated and plump, but sometimes there's a slight flush. By day 3, you get that 'lit from within' look. For oily skin, that timeline is perfect because the treatment reduces surface oil but your natural balance returns by then, so you won't look greasy – just healthy. Definitely don't do it the day before, as any micro-reactions need time to settle.