Azelaic Acid Serum

How long would it take for this to start working? And how many times is it recommended to use this?

Use every morning and night for supple skin

Lovely product. It's easy to use and does what it needs to do. I've been using it for years and I have acne, but partly because of this, my house is not scarred. Two pumps in the morning and it lasts for months, so the price tag is relative.