Sending luggage ahead?

I will be walking the Camino to Santiago de Compostela in N. Spain this Sept and, because of its length (800 kms), would like to carry only my 35L daypack. After the walk, I'll be spending another three months in Europe and the middle east so a daypack won't cut it for luggage. My question: does anyone out there have any suggestions about sending my luggage ahead? After the walk, I'll be going directly to Lisbon. Should I send my backpack there by courier from home (Canada) or should I bring both bags to Madrid (before the walk) and ship the larger bag by courier/ train/ bus to Lisbon? What about storage?
Any experiences, suggestions, or estimates of cost would be a great help.
Gracias

Wow, that's going to be difficult! I would send it to Lisbon. Do you have a place in Lisbon to send your packages? DO you have any friends or something? If not what I would do is to contact your hotel in Lisbon, let them know that you are sending your luggage there and ask them to hold it for you. If you do this, schedule the package to arrive 2-3 days before you get to Lisbon, so the hotel won't complain that much. Use FedEx or UPS and before you leave write down where are their offices in Lisbon. Another suggestion is to bring only the backpack and then buy whatever you need in Lisbon. I don't know how cheap are clothes/shoes there but I think it is cheaper than in Spain.