No, Illinois does not allow carryovers for classroom ethics. It does allow up to 12 credit hours over to the next compliance period.
Example, your license ends on February 28, 2018 and you renewed your license on February 10. Your new compliance period starts on March 1, 2018 and ends on February 28, 2020. You take an ethics class on February 21, 2018. You will get no credits for your new compliance period because it was done before March 1, 2018.
Second example, you complete 12 hours self study course on February 22, 2018. Those hours can be carried forward to the new compliance period ( 3-1-2018 to 2-28-2020)