Sphinx,
I dont know abt other centers, but heres one case from here in kerala.
till 2002 in malluland the CAT center was cochin. Cochin being a bigger city had many hotels and schools to hold exams. But in 2002, we had a shock! The center would be kozhidkoe. there was mad rush for forms and ppl submitted early. there were some ppl like me who submitted towards the end. The general thought was the kozhikode being a smaller city, the centers would get filled up faster. but nothing of that sort happened. I got the center as kozhikode.
But that does not mean that you need to submit it late

earlier the better. why take chances, like Arun mentioned earlier, dont be the first to make history....

Take care