That information from the log (not actually an error) probably will only be triggered if you are running certbot renew, right?
You might try certbot renew --force-renewal, but I’m not sure what will happen. It will probably just renew the certificate with a new test certificate, because in the renewal configuration the server option is set to the staging server and the account setting to a staging account.
If it did work, just be absolutely sure that --force-renewal isn’t added to your renewal configuration files in /etc/letsencrypt/renewal/!
My advice would be to remove the --test-cert flag before you run certbot renew: i.e., get a real certificate with the initial command you used to get the test certificate, but without the --test-cert flag.
After that, you can test renewal with certbot renew --dry-run.
If you’re trying to do what @Osiris suggests and still seeing “Cert not yet due for renewal”, add --force-renew to your command line (just this one time to make it switch over, not always in the future!).