This has been my major issue since the beginning of the application process...I took the DAT back at Christmas break and am retaking at the end of this month:
That being said there were a couple of options that people came up with:
1) Wait till after you have retaken it to e-submit. This ensures that the first time schools see your application will be with your 2nd score included. Keep in mind it can take 4-6 weeks for AADSAS to process your application, as well as verifying transcripts and LoR matching could push that date forward as well.
2) An interesting idea put up on the forums, was E-submit now and only appoint a school that you know you will not be attending. after you have retaken the DAT, appoint the remaining schools on your list, and by the time it gets sent out your new DAT scores should be available. This is kinda theoretical because when I asked the AADSAS they seemed to not know if this would work or not. Aka try at your own risk.
3) Esubmit now, and contact all the schools you appointed letting them know to hold your application until your DAT scores are available. Some schools will allow you to Fax your DAT scores when you get your unofficial score sheet the day you take the test--some will not. From what I understand some schools will not even hold your application (don't quote me on this).
The bottom line is that if you are retaking the DAT this summer, the entire application and time line is a mess. Nothing is for sure about when the best, earliest time to apply is. All I can say is the earlier the better.
Some facts that may help in deciding:
--4-6 weeks for AADSAS to process applications, GPA check, and get them sent out as long as they recieve your LOR's and Transcripts and everything works out there.
--It is important to send LoR's and Transcripts ASAP as they can be processed at any time during the process.
--2-3 weeks for ADA to send the official scores to the AADSAS once you retake the DAT. They have an official auditing process for each score to make sure that everything is cool.