When did SF start using numbers

San Francisco was allocated examiner numbers 1461-1740 by General Order 4 on 19 December 1941, This allocation was continued in General Orders 24 and 56 on, 2 February and 1 May 1942, respectively.
In looking at early censored covers from SF, I have seen several with B&M C 1,1,3 used without numbers, with dates of arrival in SF ranging from late December to late January:


Right now my early number use dates from (probably mid-) March:

Would you please check your SF covers and let me know what dates you have that would close this gap.
Thanks,
Dann
In looking at early censored covers from SF, I have seen several with B&M C 1,1,3 used without numbers, with dates of arrival in SF ranging from late December to late January:
Right now my early number use dates from (probably mid-) March:
Would you please check your SF covers and let me know what dates you have that would close this gap.
Thanks,
Dann