I saw this article (https://ttlc.intuit.com/turbotax-support/en-us/help-article/state-taxes/handle-state-new-jersey-resident-works-new-york/L85v9ezYr_US_en_US?uid=m94f39om), which state at the end that I should prepare NY return before NJ return. Can you help clarify what I should do if I accidentally prepared the NJ first?
That's ok. But you won't be able to finish your NJ return until you finalize NY. So you should complete NY, then come back to NJ now that the information for the credit for taxes paid to other states can be completed.