During the day your skin has to defend itself against UV radiation, pollution and stress. At night it wants to recover and repair. Out of that difference come pretty clear rules about what product belongs when.
The top goal of your morning routine is protection. Protection against UV radiation, against free radicals from pollution, against drying out from heating or air-conditioning. Your morning care should therefore:
What you don't use in the morning: retinol, AHA/BHA acids, vitamin A. They actually make your skin more light-sensitive in the short term, which is exactly the opposite of what you want during the day.
At night your skin is in "repair mode". The skin barrier rebuilds, old cells are shed, collagen is formed. That's exactly when it makes sense to work with more active ingredients that support this process:
What you don't need in the evening: sunscreen. Obviously — the sun is gone.
You don't have to do every step. Just consistently doing sunscreen in the morning and cleansing + moisturiser in the evening already makes the biggest step forward.
Vitamin C — morning, evening, or both? Both work, but morning is the classic, because as an antioxidant it provides the most benefit during the day. If you also use it in the evening, split it across two different products to avoid irritating your skin.
Niacinamide — when? Doesn't matter. Niacinamide is very well tolerated and can be used both morning and evening. Also in combination with retinol or acids.
Hyaluronic acid — when? Whenever your skin needs moisture. So: usually both. But especially in the evening, when it has time to work overnight.
Sunscreen at night? No. Waste — the UV filter only works during the day. Unless you're sitting in front of a screen all evening: even then, regular daytime sunscreen is enough, because it also filters some blue light. Otherwise just normal evening care.