In unemployment calculations, the quarters used to calculate benefits will change the first full calendar week of the new quarter, not necessarily the date of the first day of the month, as in Jan, the new quarter will begin on Jan. 7, and that is probably going to be a better week for you to file. Of course, you could file any week that you make less than your weekly benefit amount, or you could, for that matter, file a claim immediately and set up a claim, though you would not be able to begin receiving benefits on such a claim until your earnings had dropped. But in your case, it may very well pay to wait.
But what is at issue is that once you have filed a claim, if you have enough wages to set up a claim, any amount, even as little as $88, you are locked into that claim for the next full year. They do not let you change your claim when the quarters roll around where if, you had filed, and they had pulled in the first four of the last five completed quarters you would've drawn much more. So you need to look at the quarters, check out the CA unemployment tables, think about your past quarters of wages before you file for benefits.
If you were to file a claim right now (in the Oct, Nov, Dec 2018 time frame that the system is in right now) the system would go back eighteen months and pull up quarters of wages. Contrary to what many people think, unemployment insurance does not take in your whole work life, like the social security programs. They only go back a few quarters, roughly 18 months. Each time the quarters change, a quarter is picked up and one is dropped from figuring your amount of unemployment benefits you'll qualify for. The system does this calculation based on their wage records supplied by employers.
From what you have told us, there might be some small earnings quarters for you there back in 2017, which would result in your getting set up for a very small amount of weekly benefits. Then since you were given more hours later, there will be bigger quarters of earnings as we move forward. If you wait until the first full week in January to file, the first of those old quarters will drop off, and they'll pick up the more recent quarters, for possibly a larger Weekly Benefit Amount. So as has been advised, you look, you think about your earnings, you decide when to file, and remember, you'll be stuck there for a year, you can't re-file the claim once it is filed.

