To be used especially if I have used retinol or tretinoin the night before

Only use sparingly if acne is flaring up

Do not use while starting out with tretinoin - perhaps re-introduce with the time, or if acne is particularly bad

Use this when skin is feeling particularly dry, and on weekends

Use every day if not irritating/too drying

If acne is not currently active, avoid using this at night in conjunction with retinal or tretinoin

Use both before and after if using Acnecide gel

Use occasionally on nights when not using tretinoin (start with once a week, to build up adherence with tret)

Avoid mixing AHAs with Tretinoin, including glycolic, lactic, citric, malic & tartaric acid and BHAs like salicylic acid.
Also avoid Vitamin C.
https://www.skinandme.com/the-dose

Avoid while actively using Skin & Me prescription as want to judge efficacy. Use sparingly if/when acne is active/bad, and sandwich with Cicaplast Baume afterwards

Consider adding drops of hyaluronic acid to this in the evening