Hi Vlogan, I don't know which, if any, Camino you have done in the past. The Frances Camino in Spain usually take about a month to complete. 2 years ago, I walked from geneva to Le Puy, then to SJPP, then to Santiago. Total time... about 11.5 weeks. It took 2 weeks to walk to Le Puy from Geneva. So... 9.5 weeks, it would take me to walk to Santiago from Le Puy! And what a wonderful walk...
But, it is much more strenuous than the Camino in Spain. Fabulous, but tiring. And France was/is about 50% more expensive to walk through that Spain - that's what I found. Yes, as other poster here have mentioned, there are many religious holidays when shops are closed. But don't be put off by that. You can always call ahead and book a place (which I often did). And the scenery, towns, and churches are gorgeous.
So... the question is - why are you in such a hurry? Can you get a bit more time to do it properly? If not, I think your time frame is too tight. Maybe start somewhere else?