I’m headed to UCLA! 
UC application deadlines are the same as for the freshman application. I believe it opens Aug. 1, and the deadline is Nov. 30. I think those are the only deadlines you need to worry about for now. You don’t have to worry about sending transcripts until you are admitted to your new school, and most UC’s don’t require a high school transcript when you transfer - if they need one they’ll let you know.
Personal statements aren’t as important as they were for freshman admission, but I suggest highlighting an activity that pertains to your major that you enjoy. For instance, I applied as a math major, so I talked about working as a math tutor at a learning center and how much I enjoyed working with the younger kids.