I think they open at 2pm. As with all the albergues, it's a first come first served.
I'm not to sure if you are familiar with the concept... you have to be back by 10pm, they will lock the door after that. You will sleep in a dorm with about 50 others, in bunk beds, although they are separated with partitions. You even get lockers in this albergue, just next to your bed, which comes handy if you want to leave some stuff there when you go to town.
And most important, you will need a Credential (pilgrims passport). If you don't have one yet, you might get one there.
Good luck, and buen camino!
Rolf