You could certainly make use of Worker Role for that purpose however I would not recommend going down that route as you are only going to use the functionality once a week. Or in other words you would be under utilizing the resources. Do take a look at Windows Azure Mobile Service Scheduler: http://www.windowsazure.com/en-us/develop/mobile/tutorials/schedule-backend-tasks/. Other alternative would be use a 3rd party service like Aditi Scheduler: http://www.aditicloud.com/. There's also a website which also allows you to do the same functionality (I'm sorry I forgot the name of that site :)).
If you're still keen on doing it through Windows Azure Worker Role, I wrote a blog post about the same which you may find useful: http://gauravmantri.com/2013/01/23/building-a-simple-task-scheduler-in-windows-azure/.