Lurker chiming in too…DO IT
In 2012 I was fortunate enough to go with my dad when I was in year 12 aged 17. I went in September which is one of the busiest times however the weather was perfect. I did the way of St James, same as user Muninn, starting from St Jean. It was only uncomfortably busy in the last 100km. This is the minimum distance in order to qualify for the “compostella” and there is a noticeable increase in “freds” to use a cycling expression.
Whichever month you choose I strongly advise you to see if there are any festivals on. Just like San Fermin in Pamplona, even pin dick towns go nuts. It’s so much fun but accommodation might be an issue. We lucked out and were in Longrono during San something. There was another in Najera and their whole town of 8000 were out with their families cooking paella using some of the most ghetto set ups. Once that rapt up everyone then flocked to the local bull ring. I was drunk and stupidly entered the arena with all the other drunk blokes when the main event finished. Meanwhile my dad is waving his arms and screaming for me to come back. I bitched it when the bull was like more than 10m away fuck they are big and angry.
As you are cycling an issue will be the priority given in the albergues to walkers. I forget but I think it’s around after siesta they let cyclists come in. Having said that there is privately owned hostels/refugios that don’t care.
The church run albergues are fine, they are cheaper some are by donation. I recommend the Cistercian nun albergue in Santo Domingo de Calzada. It is donation, quiet, has a beer vending machine in the dining area and kitchen.
If crowds aren’t your thing you could try one of the many other routes available. The “Del Norte” route, which follows the northern coast apparently, is amazing. The weather is less predictable.
Muninn is spot on about the roads but it sounds like you’ll be right. There are also some nice detours that aren’t way marked such as the “dragonte” route near O’cebriero in Galicia. You will have to walk your bike etc for a little bit if you choose to do these. I recommend the detour to Eunate where there is a church that was built by the Knights Templar. We didn’t but you can stay in the caretaker couples house there if you want.
Register as a pilgrim don’t worry about the reason because you need the passport its like having a concession card (most albergues won’t let you in without it) you can get cheaper transport apparently and you get 50% off purgatory if you finish (lol).
Suss some guide books. We combined like 5. The Brierly one is the most popular. It contains awesome information about accomodation and other random useful things. But, he is an old man and is really spiritual and “glorious” is the only adjective he uses. An Aussie bloke made a durable ring bound map with essential info, that one we found was the most accurate map. I’ll try and dig it out.
I had so much fun I vowed to save and do it again. In fact this Friday I am leaving to do the Via de la Plata starting from Seville. It is in winter this time and it is a lot longer and the towns are even smaller. I’m at uni now so this is the only time I can take off. Can’t wait!