Since this question relates to those whom are applying at the same time, early is being earlier than the masses you are 'competing' against. If I had to do it all over again, I'd get everything ready to submit the first day that Submit button became available. I'm sure the first month is still fine. Just be sure to feel confident that your PS is strong. The secondary benefit of being the first day is that I imagine the validation step would be far less than the month+ that it takes during peak submission times.