No it doesn't matter. If you have 100 grams of fresh mushrooms, you will have around 10 grams of mushrooms left when you dry them. The only difference is that the water is gone. But if you store them for a few months it depends on the psilocybine/psilocine ratio in the kind of mushrooms you have. Psilocybine is stable and if for example you dry psilocybe semilanceata they will be dried as potent as when they were fresh (because allmost all of it is psilocybine). If they are psilocybe cubensis the ratio is around 50/50 and if you store those for half a year you have to take a double dose for the same effects, because the psilocine is unstable and because of that they will loose 50 % of their potency.
Hope that helps.