Anonymous wrote: Thanks
If it's a supplemental piece of the application (things not within the applicant's control, such as teacher recs, SSAT scores, etc.) and you can give them a firm date — "I talked to our school and you'll have the recs by Friday" — you should be fine.
If it's information within your family's control, it's a problem for schools that have more applicants than they can accommodate. Most of them will, as a PP noted, only consider the application after they've completed the first "wave." At the most competitive schools, that makes it nearly impossible to gain an offer of admission, absent an unusual circumstance. Other schools vary.
Hope that helps.
Peter
____________________
Disclaimer: The anonymity here makes me uncomfortable; it's easy to be uninformed, personal, or simply mean-spirited if people don't identify themselves. For that reason, I have an account so you know whose words you're reading. I have more than 20 years' experience as a teacher and administrator in independent schools, and I have counseled hundreds of students in finding their next schools. I hope I can be helpful to some folks. If you don't like something I've said, you're in good company — there's a long line of past students and parents ahead of you.

If you want to chat further, please feel free to contact me offline: peter <at> arcpd <dot> com