Do I need to report the SAT I take in December to UCs?

On my UC app I wrote that I would be taking 3 subject tests this December. If I do poorly on one do I still need to send it to the UCs?

My main concern is my application taking longer and thus being more harshly judged. Should I send my SATs as soon as possible by bubbling a UC school at the testing center or should I wait to see what I get on these most recent subject tests and then send in choice ones?

Thanks so much!