I just finished walking the del Norte / Primitivo combination. The arrrows on that route are are quite good but I didn't know where to start officially either. I did start though at the bridge to Hendaye, just so I could say I walked from France. There were arrows on the bridge and through Irun.
I found that using maps.me on my iPhone along with downloaded gps files of the Camino routes was very useful to reassure me and get me back on the right route when I accidentally (or purposely) went off course. The app is free, an off-line map, i.e., works in airplane mode and is easy to use.
I had the up-to-date Cicerone guide on the Northern Caminos bit rarely looked at it. Maps.me has all the albergues, hotels, etc on it but we also used the Gronze site and booking.com. Most places we stayed in were cheap pensións or hotels with a sprinkling of albergues and casa rurals. I have a summary in my blog, if it helps, and I trying to expand on it now.
Buen Camino!