It's terrific that you recognize that the California Bar is so important to firms in this state. It's not easily waived in to and therefore, takes a great amount of effort to become a member. What's great about this is that by registering for the California Bar (and by taking the Bar), you are indicating to potential employers that you are serious about your move to the West Coast.
You certainly have the best chances at securing an interview and a position if you are a member of the Bar. However, at this stage, the Bar is of varying importance depending on your practice area. I have placed several transactional attorneys, for example, that were not barred in California, but had planned to take the next upcoming examination. Should you receive an offer, a firm may pay for related Bar expenses. (However, I do not recommend waiting on the Bar until you have an offer!)
For litigators, not being a member of the California Bar is a much larger hurdle. Often recruitment coordinators will not glance at a litigation resume for a present position if the candidate does not already have the Bar, even if this person is from a top #10 law school and has outstanding experience.
However, no matter your practice, if you decide to make a move to California and are not presently a member of the Bar, you should still start investigating openings. Even if you decide to hold on submitting your materials, it's good for you to get an idea for the market, which firms are looking, and what credentials they seek. This will give you a tremendous advantage for when you do decide to move forward with your applications.
See Guidelines on Reciprocity or Admission On Motion among the States as per American Bar Association for more information.
Another factor to consider is that, unless there is an imminent need, firms are taking a longer time at the interview stage. It's not out of the ordinary for the process to last several months. If you have taken the Bar but have not received your results, or your scheduled exam is less than a month away, it may be a good idea to submit for positions anyhow (even if you are a litigator). It's better to get your materials in front of a desired firm when you have the chance, rather than gambling that the firm may have another open position after you obtain your results. Then, when you receive your results (and they're positive), make sure to contact the hiring coordinator at the firm (or your recruiter) to give them the good news!