From NYC to where? Paris, Barcelona, Madrid or Lisbon? Then you are a full day or more, to SJPP. If you end up at Pamplona or Bordeaux at the tail end of your first day, then I suppose you would get to SJPP early enough to walk up to Orisson. I wouldn't though...the afternoon in Saint Jean is well spent having a meal by the river, checking in at the Pilgrim Office and preparing to begin. Also, I highly recommend staying in Roncevalles. The first night and dinner is a kind of right of passage, not to miss.
Just my opinion, but with 7 weeks, you have more than enough time to enjoy the towns along the way.
Just saw that you arrive in Pamplona at 9 am. I think I would still take a bus to SJPP and enjoy the rest of the day there- it's a bookend to your journey and worth the time.