If you have been meaning to start using vitamin A on your skin and keep putting it off, the next few weeks are the window. There is a practical reason for that, and it has nothing to do with a seasonal sale.
The reason is the sun, not the calendar
Vitamin A makes skin more sensitive to sunlight. That is not a scare story, it is simply how it behaves, and it is why every sensible instruction leaflet tells you to wear sun protection during the day.
In Northern Europe, the UV index drops sharply between late August and October. In the Netherlands, Germany and Sweden, the difference between a July afternoon and an October afternoon is substantial. Starting in September means your skin goes through its most reactive weeks at exactly the time of year when there is least ultraviolet light around to complicate things.
Starting in June means the opposite. It can be done, and plenty of people do it, but you are making the first six weeks harder than they need to be.
The adjustment period lines up neatly
The first weeks on vitamin A are the awkward ones. Some dryness. Some light flaking. Occasionally a patch that feels tight. This settles, but it takes time — usually four to six weeks before skin stops complaining, and eight to twelve weeks before you can fairly judge what it is doing for you.
Count that out from early September and you arrive somewhere around late November with skin that has already adapted. Which is convenient, because that is when central heating starts drying everyone out, and you would rather not be dealing with two things at once.
What starting properly looks like
Weeks one to three. Two evenings a week, no more. Clean, dry skin. A pea-sized amount for the whole face, warmed between your fingertips first. Your usual moisturiser on top afterwards. Sun protection every morning, even on grey days.
Weeks four to six. If your skin is calm, move to three evenings a week. If it is not calm, stay where you are. There is no prize for going faster, and the people who push through discomfort are the ones who give up in month two.
Weeks seven to twelve. Most people settle somewhere between three and five evenings a week and stay there. Some skin is happy every night. Some skin is happiest at three. Both are fine.
After twelve weeks. Now you can judge it. Look at texture, and at the fine lines around the eyes and mouth, in the same light and at the same time of day. Photographs taken in identical conditions are more honest than memory.
The mistakes that make September pointless
Starting every night because you are impatient. This is the most common one, and it is the one that ends in a red, sore face and an abandoned tube.
Layering it with acids on the same evening. Give exfoliating acids their own nights, at least while you are adjusting.
Applying it to damp skin. Wait until your face is properly dry.
Skipping sun protection because it is autumn. UV does not stop in October, it just gets quieter.
Stopping the moment you flake. Light flaking in the first weeks is expected. Tight, sore, angry skin is not — that is the signal to drop back to once a week and rebuild.
If you have tried retinol before and it went badly
Try again, but slower than you think is necessary. Most people who report that retinol does not work for them started at four or five nights a week, met a wall in week two, and stopped.
Once a week for a fortnight, then twice a week for a fortnight, then reassess. It feels absurdly cautious. It also works.
The short version
Start in the next few weeks, not in the spring. Two evenings a week. A pea-sized amount. Moisturiser on top, sun protection in the morning, and give it until December before you decide what you think.
