I have this. I keep it inside it’s box and keep it inside a drawer to keep it away from the sunlight. After a while it would turn pale yellow and it still okay, if it turns dark yellow it would be oxidized
Yes. I use it almost everyday. Just a few drops or 5 on my face without the tips touching my skin.
I used it in the morning because I use retinol at night and that did irritated my face. I used it after cleanser, toner, exfoliator, and serum. I don’t use moisturizer in the morning because all my other steps is enough for me and my current sunscreen is moiturizing enough, if I do use moisturizer I used before moisturizer.
Then I let my the products absorb and dry a bit. It takes a few minutes before applying sunscreeen.
An even lazier morning would be cleanser, Vit C and sunscreen.