The "scramble" is only open to people who have registered with the NRMP and have failed to match. Therefore, you'd better get on the ball and take Step 1 soon if you really want to match this year.
After the scramble is over, there may still be some positions open which would be available to those who didn't participate in the match, but these would be chicken scratchings, at best.
I can understand not wanting to wait out a year, but by not getting things done in a manner timely enough to participate in the match you are severely limiting your residency choices by having to scramble. Most of the best spots will be taken, especially in California (ie, there may not be any spots to scramble into) - are you willing to take this chance?