As others have said, consider your return flight. IMHO, I would fly to Madrid, then bus or train Pamplona and bus to St Jean. When your Camino is finished, it is easy to get from Santiago to Madrid by train or bus. To get the cheapest flights, use Skyscanner which will show the cheapest flights in every month, and then see if your Camino will fit between those dates.
For example: Lufthansa/Air Canada, Dep.Vancouver 1 May to Madrid, 1 stop at Toronto; return by Lufthansa/Air Canada 1 June from Madrid; 1 stop at Toronto, Total cost $1373. There are other airlines on same dates for $1374. With these prices in mind, go to one or more local travel agents to see if they can beat the price. Arrival time in Madrid is 0755 so it is possible to get to St Jean the same day depending on when you travel. But you would need a rest day to recover from the jet lag.
I have used hypothetical dates to get an idea, but you can put in your own dates on Skyscanner, and they will give you the fares for all airlines on that date