NOTAMs have been issued, effective on 19 January (when 5G is turned on). Example:
!FDC 2/3714 SFO IAP SAN FRANCISCO INTL, SAN FRANCISCO, CA. ILS RWY 28R (SA CAT I), AMDT 15A ... ILS RWY 28R (CAT II - III), AMDT 15A ... ILS RWY 28L (SA CAT II), AMDT 27B ... PROCEDURE NA EXC FOR ACFT USING APPROVED ALTERNATIVE METHODS OF COMPLIANCE DUE TO 5G C-BAND INTERFERENCE PLUS SEE AIRWORTHINESS DIRECTIVES 2021-23-12, 2021-23-13 2201190500-2401190501EST
Now the fun starts....