If the claimant grosses $2,250+, then the claimant will have purged the disqualification no matter what. The earning requirement is 5 x the Weekly Benefit Amount. If the claimant earned less than $2,250 then they still might purge. CA's max WBA is $450 so at $2,250, it's assured.
However, the claimant might quit or get fired under disqualifying circumstances, or the job might end early under qualifying circumstances without meeting the earnings requirement. The client might keep the temp for a very long time. There might be a refusal of work involved so whether the claimant will actually collect can't be know for sure until the assignment ends.
By "first" do you mean former employer's account or do you mean the temp job's account?
It goes against the former employer because those were the wages used in the benefit calculation. However, this new employer will have some chargeability in the event there is a 2nd-year claim, and the former employer will get to pay more. CA only requires $1,300 earned in one quarter during the benefit year to show attachment to the labor market. They would then get to use their earnings from after the end of their base period to the date they applied for UI, and maybe the wages of the new employer if they fall within the 2nd-year claim's base period.

