Welcome to the forum. I see you already have the information re Orison. You say you feel nervous, but I think that is normal and as you get to St.Jean-P-de-P your nervousness will probably be turned into adrenalin, but don't let it push you too hard on the first day. Walking in October you will meet other pilgrims who will be a help and support along the way and, after a day or two, you will feel comfortable as you meet up each night with fellow pilgrims in the refugios.
By the way, I've stayed at Orison, the welcome is very good, and if you get clear weather you will have a wonderful first day - the views are spectacular.