if your skin is dry there is a good chance there is excess dead skin so I would recommend you put a lot of focus into ex foliating well before applying moisturizer.
Make sure you throughly wash off the moisturizer before the spray tan application...also probably best not to moisturize 24 hrs before just to be on safe side
HTH and good luck I'm sure all will go well
Also be aware of which exfoliators you use, some contain products that actually act as a barrier to the spray tan. Use something natural or check that it isn't oil based or promises to nourish the bejesus out of you.LOL
As Collin says, ideally 24 hrs before a tan for moisturising. Ask the technician if she has those "body polishing wipes" they prep your skin removing traces of moisturiser and natural oils.o you can exfoliate and moisturise then wash it off as best you can about 4 hrs before your tan and then the wipes will hopefully remove any further residue