Start now - the better condition your skin is in, the better it will stand up to treatment. I have had 14 rads now with no ill effects, but a bit of tightness goes away with a good slather of cream. (But not in the 2 hours before treatment.) My rads oncologist favours Essentials pure Vit E cream (from any chemist) which works well for me, and isn't greasy, as they prefer cream without oil in it. If skin gets a bit burned later in the program, he suggests pure aloe vera PLUS the cream, as on its own it can be quite drying. I am sure sorbelene does the job as well. All the best for Tuesday - it is really easy so don't worry yourself - Michelle x