Keep asking, and try to do it at a time when the person you are asking is not in a rush - as you become accustomed to the rhythms of the office who and when to ask will become clearer. Make sure that you know what your immediate supervisor wants from you and that they know you are getting yourself up to speed - I'm sure they will be aware that like all new hires you are on a learning curve.
If you can find the papers you need and get to page 151 of a spreadsheet in 20 minutes when starting out in your profession in an unfamiliar office I can safely predict that you will do just fine.