I'm really not an expert at all with this, since I am actually going through this process right now myself. However, I am pretty sure (or at least with all the schools I have called and bugged) that your application is not considered complete until they have gotten your LOR. So if you want to be an early applicant you might want to get that ASAP. As far as turning it in to AADSAS, I believe that if you wanted you could completly bypass them and have your LORs sent directly to the schools you are applying to. Don't take my word on this though!!