I applied by the December 15th date. Although my GRE scores did not arrive until a few days after the 15th so I'm not certain if they treated my application as early decision or regular. I received a letter by regular mail. GOOD LUCK! It seems decisions trickle in over a two-month period.
I had the same question and was given some very helpful information from a professor, which is that no committment signature is biding. They might not be especially pleased, but it's done all the time and it's not a legal contract. If they ask you for money to reserve the spot, however, you have to be willing to lose the money and that's not even necessarily so as sometimes they will refund.
I applied to CSULA, CSUN, USC and UCLA and have been accepted to CSULA so far. Waiting on the others. I just signed my committment letter yesterday and returned it to CSULA because from all that I read across the threads and from professors with experience, the prestige schools don't necessarily promise anyhing better. I'm wondering how others feel about the price of a graduate degree?
Re: UCLA. I applied by the Dec 15th deadline and would only hear back if I inquired about particular materials. I wanted to confirm they had received my final transcripts and they did respond. They never sent the GRE email confirmation that they stated they would send. Also -- last year applicants got their decisions from mid-February through April.
Not yet time to panic, more than likely. It's really early. :-)