Transcripts get sent to AMCAS, LOR's get sent to each school (office of admissions).
Have you started to fill out your AMCAS application yet? Midway? If you are done and submitted or soon to submit you can send your transcripts. You don't want to send your transcripts/LOR way ahead of submission because they have don't have your submitted file yet.
I spoke to my pre-evaluation committee advisor ahead of time before I submitted my AMCAS, so he already prepared my LOR...he said once I submitted I should just give him the word and he will send out the LOR pronto. He didn't want to send my LOR too early, because the school will have no idea who you are until you submitted your AMCAS.
Just make sure everything gets there around the same time...