I'm not sure that there is a "too late". If you aren't past the deadline and you want to apply, I would just go for it. Anecdotally, I know of at least one member here who didn't even submit their primary for screening until the beginning of October, and still got accepted by a couple of schools (including one that is pretty highly ranked). Obviously their chances dropped significantly at most schools they applied to, and they likely would have been accepted to many more had they applied earlier, but it just demonstrates that at no point is it a guaranteed rejection due to completion date.