You can send transcripts as soon as you are able to create an AMCAS account and you can get to the transcript request page (basically just a page that has your AMCAS number on it) so that your transcripts, when sent, will go to the right place.
As a reapplicant will I have the same AMCAS number as before? Im only worried because the school where i got my masters says it takes 7-10 weeks so I don't want to have my application incomplete because its waiting on that.