All depends on the state, and I'm not personally familiar with PA law.
Some states, it's as soon as you declare residency (by renting an apartment, buying a house, etc). Others may make you wait from 60 days to 6 months.
"The only real difference between the men and the boys, is the number and size, and cost of their toys." NRA Life, GOA Life, CSSA Life, NRA Certified Instructor, FFL/SOT 07/C2