When I was in my 40s, there were conflicting recommendations. ACS said yearly at 40, ACOG said yearly at 45, USPSTF said yearly at 50.
I am low-risk and waited to 48 to start. During that time, I was being periodically reminded by FB friends who had caught DCIS or even higher-stage breast cancers via mammograms done early how important it was to do this.
Usually these folks did not share information about their own risk factors, which can be quantified using this tool:
https://magview.com/ibis-risk-calculator/ (warning: it's a long intake--quite thorough).
To date, I have not gotten breast cancer, and earlier mammograms would not have impacted any breast cancer I might eventually get. It was a good choice for me.