You would begin collecting the 20 hours during the 2 year period. If audited, you would need to show that you had attended the 20 hours of continuing ed between May 2010 and May 2012 (if that is when they decide to start). The letter that will be sent from the IL DPFR should also describe the types of credit that can be obtained to be credited to the 20 hours. From what I understand, nurses will not be held accountable for having the 20 hours for the 2008-2010 period.