Medical exam reports are valid for 2 years and the medical exam report should be issued by a civil surgeon no more than 60 days before the date the applicant filed the green card application. USCIS temporarily waived this 60-day requirement effective December 9, 2021, and will be in effect until September 30, 2022. However, it is highly recommended that an applicant makes an effort to adhere to the 60-day requirement to avoid unnecessary inquiries from USCIS
You can submit your medical examination report along with your green card application or when the USCIS issues a Request for Evidence (RFE) for the same. Sometime, the USCIS simply requests you to bring your medical examination report to your interview at the local USCSI field office.