Day one is actually a very challenging day, mostly uphill, and probably under the burden of too many things. In our case, these things were foodstuffs. You don’t need to carry food on this hike, and unless you absolutely must, you probably wouldn’t want to.
The road leads you to Roncesvalles, where most Spanish people begin their trek, and the site of the first official Pilgrim’s mass. Go to it, but first, make a reservation for dinner (you will need to get into the habit of checking to see if one is needed wherever you stay). You could be waiting a long time to eat otherwise.