Have you ever woken up one morning with a pimple glaring at you?.. and wondered what you did or used the day before that caused it to form. Well just like it takes time for the pimple to go away it also takes time for it to form. How Pimples Truly Form Even though it seems as though the pimple appeared overnight it's actually 1-2 weeks in the making before it's fully developed. This long process starts off with our oil glands becoming over productive and pump out excess oil.