How about the other way around? Can the professors submit the LOR electronically BEFORE you submit your application online? I would prefer to wait until August so that I can include my summer grades, so can my professors submit the LORs electronically before I submit an application? Or does it have to be after? I'm not sure how this works... 
your professors can submit the LOR electronically as soon as you create an account. Aadsas does have some LOR forms you have to print out from their website. Your gpa better be 3.7+ to be submitting at the end of august to ensure you have no problems. Aadsas takes about 7 weeks just to send out applications if you wait til august. This doesn't include secondary applications the school wants (some schools make you write additional essays).
You probably won't be interviewing until late october or november. I wouldn't take applying early lightly because things don't go as planned and alot of times your application isn't complete due to no fault of yours. Some schools do lose stuff or say you didn't take certain classes.
Well if you feel you need to wait until august, get everything else done and put up on aadsas so all you are waiting for are your grades. Good luck, whatever you decide.
To answer the OP's question, you can submit your application starting may 15 on aadsas. You can submit your application without dat scores, LORs etc. All aadsas will do is verify your grades and send out your application (this includes personal statement, your information, grades, extracurricular activities etc). Once they receive your LORS, they will send them out to the school. You can track all this on their website. Aadsas has nothing to do with your dat scores. You need to request those from the website where you signed up to take the dat.
Your application with the schools will not be complete until they have your: aadsas application, LORS, dat scores, picture (if one is required) secondary application (if one is required), and secondary application fee (if one is required). When I say complete, this means (most of the time) they wouldn't even look at your application.
Oh yea and with some schoosl, secondary application are not automatic. They is a link of aadsas about secondary applications that will be helpful. It lets you know what schools expect what, where to send them to etc.
Some schools are good about sending you a letter informing you on what you are missing.
Hope that helped!
