What is the best time to apply?

So each college does have a ‘deadline’ to submit applications. But I have heard several people say that its best to apply early so that you are ‘on top of the pile’ and you definitely shouldnt apply too late. But also, one can intuitively say that you also dont want to be one of the first applicants to be read, since the adcom will probably expect better applications to come.

So my question is, what would be the ideal time to apply?

Specifically: For ED UPenn, how would October 10 be. Early, late, right in the middle?

And what about RD. I really want to submit my RD applications only after my ED result obviously to save the money, but will 15 December be too late an RD date?

For these colleges that you want to apply to, it does not matter how early you submit. Earliness is not a factor in their decision. Just get them in by the appropriate deadline.

Earliness CAN be a factor in merit aid which may run out or have an earlier deadline. And for those schools with rolling admission it does make a difference.