Don't worry, this is very normal. My transcript was sent out June 4, but AMCAS didn't receive it until June 17. Apparently, it takes 7-10 days for mail to get there (regular; next day is, of course, next day) but it takes AMCAS up to 10 days to process the transcript and indicate that on your status page. So, it may take up to 20 days after your transcript is sent out that it will be marked as "received." Also, it takes 4-6 weeks for the application to be verified, so your application won't actually get to the medical schools until a month or so from now.