The reciprocal agreement always applies to your resident state, so since you change resident states, you will have to file the part year tax return for Pennsylvania and New Jersey. You can file the New Jersey part year with the income from when you lived in New Jersey than file the nonresident NJ income for the time you were a PA resident. Then you can file the PA PY with the income while you were a PA resident and claim the credit for taxes paid to New Jersey.