Congratulations on your camino!
As Laurie suggests, by starting in Jaca you are missing some amazing landscapes, I would most definitely try to start a bit higher up the mountains, particularly
1) take the train to Canfranc station, it is like a trip in the past, perched along incredible cliffs in beautifuly valleys . The Canfranc station is amazing, you can look for information about this amazing place in the Internet. Worth the extra day
2) if the weather is fine and there is not a lot of snow, you can start in Somport, for which you have two choices
2.1, take the bus from Canfranc to Somport at noon, then walk back to Somport, it is about 10 km in dramatic mountain landscape. You can them sleep in Canfranc
2.2, you can take the bus from Canfranc to Somport in the afternoon, sleep in Somport (2000 meter altitude), then start walking the following morning: it is some 10 km to Canfranc, then 24 to Jaca, 34 in total, it might be a long day, but you can also stop in the new bucolic private hostel in Castiello de Jaca
http://www.gronze.com/aragon/huesca/castiello-jaca/albergue-anoguera
IT is defeinitely worth it to statrt in the Pyrinees, if you do have a chance, go for it!