Should i use the same amount of tretinoin every night or gradually increase it like i did with benzoyl peroxide?

No: Only use that medication as it was prescribed. There are many possible adverse effects so it is important to follow up with your doctor to monitor how you are doing.

Tretinoin: The typical amount used should only be a "pea size" this is enough to treat the entire face. See a dermatologist since there are different strengths of tretinoin with different formulas or vehicles eg. Cream or gel form. At times the patient may need to use tretinoin every other or every third night if overly dry or sensitive skin exists.

Gradually: If your skin is not oily, i would start by using it every other night only. If your skin does not get too dry, you can increase to nighlyt. A pea sized amount is enough for the whole face. Some driness in the beginning is normal and will disappear with continued use. Rember this product makes your skin more sensitive skin, so be sure to wear a sunscreen.