If you don’t want to start walking on the Camino on the day when you arrive at your starting point, you can sleep in an albergue, the only requirement is to have a Credential (pilgrim’s passport) that you can get at the Pilgrim’s office or in bigger albergues. However you don’t need to stay in the albergue where you buy your credential, you can choose another one.
Please don’t forget that usually you can stay only one night in the same albergue.