Twelve hours cannot improve your skin. They can absolutely wreck it. So the plan is small on purpose.
Every bride is offered something on the last night. A sheet mask someone swears by. A quick clean-up because the parlour is open. Threading, because tomorrow there is no time. Skin simply needs a little settling time, so all of this works better a few days earlier — the same treatment, booked at the right distance from the day, gives you the glow without the risk of last-minute redness.
Your normal cleanse, your normal moisturiser. Nothing else on your face. Water through the evening, and less salt at dinner if you wake up puffy easily. Everything laid out — outfit, jewellery, chargers, the artist's arrival time, who is opening the door. Phone away by a fixed hour, with one person deputised to handle calls. Sleep. Seven hours if you can get them. This is the entire treatment.
A facial, clean-up or extraction squeezed in tonight. Skin likes 24–72 hours to settle after one. Ideally book it 7–10 days before, and keep tonight for rest. Threading or waxing the face. Small bumps and pinkness are normal for a day and photograph badly under flash. A first-time sheet mask or overnight peel. The one night when an unfamiliar ingredient is least survivable. A very late night 'because it's the last one'. Under-eye shadows and puffiness are the one thing makeup genuinely struggles with.
The most beautiful thing you can put on your face tonight is seven hours.
Nothing new on your skin. Nothing at all. Water early, salt low, phone away. Sleep — the single highest-return decision left in the entire countdown.
Better a few days earlier. Skin usually needs 24–72 hours to settle after a facial, clean-up or extraction, so the ideal last facial is about 7–10 days before your first function. If tonight is all you have, keep it to gentle hydration with someone who already knows your skin.
Only if it is one you have used several times before with no reaction. The night before is the worst possible time to meet a new ingredient.
Something familiar and not very salty, and water through the evening rather than a litre right before bed. Puffiness on the morning is mostly salt, alcohol and short sleep.