Hi John,
If you are planning to walk from Oloron Ste Marie to St Jean you will be on the Chemin du Piemont route. It is about 5 days walking to St Jean and another 3/4 days to Puente la Reina (You can do longer stages though. You will find maps and info on this website:
http://vppyr.free.fr/
Oloron-Sainte-Marie 23,2
L'Hôpital-Saint-Blaise 18,6
Mauléon-Licharre 15,6
Saint-Just-Ibarre 21,0
Saint-Jean-Pied-de-Port 20,5
Roncesvalles 28
Larrasoana 27
Pamplona 17
Puente La Reina 22
It is another 685kms to Santiago from Puente la Reina and you would really have to push it to cover that distance in 22 days.
If you are planning to walk over the Somport Pass you will be on the Arles route until the pass and then on the Aragones until Puente La Reina. It will be about 11 days to Puente la Reina. You would have 24 days to get to Santiago - it is doable if you are a fit, fast walker.
You will find stage maps for this route here:
http://www.aucoeurduchemin.org/spip/?lang=en
23 Oloron-Sainte-Marie
21 Sarrance
22 Borce
25 Canfranc Estacion
25 Jaca.
25 Arres
28 Ruesta
22 Sanguesa
18 Izco
23 Tiébas
18 Puente la Reina