When is the latest a certified copy can be filed for the patent to include the foreign priority claim without a certificate of correction?

The certified copy of the foreign application must be filed before the patent is granted. If the certified copy is filed after payment of the issue fee but prior to the date of grant, the priority claim will be placed in the file record but the patent will not include the priority claim unless corrected after the patent is granted using a certificate of correction under 35 U.S.C. 255 and 37 CFR 1.323.

For applications filed under 35 U.S.C. 111(a) (other than design applications), a petition under 37 CFR 1.55(e) to accept an unintentionally delayed priority claim must also be filed with the certificate of correction. For all applications, a grantable petition under 37 CFR 1.55(f) or (g) must also be filed with the certificate of correction unless the priority claim was timely made but a certified copy was not yet in the file. See MPEP 215.03.