Does overtime count for the two year minimum of experience for certifications?

Was told by my educator that I would be eligible for certain certifications at my unit and I decided to look some of them up. While the amount of experience in said specialty varies from certification to certification, just about all of them require 2 years of experience as an RN at the minimum. Was curious as to whether or not overtime could contribute to the hours needed for those 2 years of experience, or I would actually have to go through the 2 years firsthand before I'm eligible for taking certifications. Would be nice to chip away 4000 hours in a year and a half instead of two.
For my oncology cert I need 1900 hours OR 1 year experience. I would say hours should count