I asked a similar question before on, If UC will accept CLEP exams as transferable credit, the answer is no. Right now I am a junior in high school. I just started caring about my grades and my future in general, my grades have been low, I am smart but didn’t try. I won’t get to the UC of my choice, so my only option is to attend Community College for 2 years and then transfer. I really want to go to UC asap.
My question is, is there any way to transfer faster from CC to UC, say within a year? Is there a limit on how many classes I can take a semester? Say I complete all my required 2 year courses in less time can I transfer right then? Or is it a requirement to spend 2 year in CC?
Thank you for your time!
There are plenty of 1 year transfers, but the majority (if not nearly all) of them have AP credits from high school that counts toward their unit count. The most units you can typically take are 18-20 units with anything over needed special permission. They often have summer sessions and I took a winter session where I earned 10 units, but it’s rather hard to earn all 60 in just a year; you really need those AP credits or need to go to school every semester possible and max out on units. You don’t need to spend two years in CC, but it certainly lightens the workload if you don’t have AP credits 
DO NOT RUSH COMMUNITY COLLEGE. Trying to cram 2 years of units into 1 year is a very poor decision - it will negatively affect your GPA, and your GPA is one of the most important factors for transferring.
Most of the UCs only accept junior transfers. There are some UCs that take sophomore transfers (I believe UCI, UCD, and UCM - I may be wrong on the specific schools, but I know for a fact that some UCs do this).
Take your time. Seriously. I know how much of a bummer CC seems to be - I was in your shoes (graduated HS with <3.0, took two years in CC, earned straight As yada yada going to Berkeley in the Fall). CC is a very good place to explore your interests and develop your work ethic.
Seriously, there’s no rush. Plenty of people, especially engineering majors, take even 3 years (or more) in CC. Take your time, college isn’t a race. If you try to rush through it, you will do poorly. The grades you earn in college will follow you if you want to go to graduate/professional school, and employers will look at them as well (when you’re first applying for jobs, anyway).
Work very hard in CC, develop good study habits, complete the necessary courses, and try to enjoy yourself. If you want to transfer as a sophomore to a UC (like Davis - I’m almost certain they accept sophomore transfers for specific majors), then you can do that - but if you take two years, you may be able to get in somewhere better.
You are right! Thank You for sharing you insightful thoughts.