Doctor changed my Adderall quantity and dosage instructions but he put a “do not fill until...

Hi, cdh!
As Jilly said, do you have enough medication to last you? Perhaps they don't want you to have the script filled until you use up your current supply?
Otherwise, you'll want to ask your doctor why.

I guess the question I have to ask is... Do you have enough pills until that date of October 7th?

When there is a change in dosage and/or quantity, you can bypass the 30-day refill restraint and refill early, usually. So, the October date prevents that, and being that it’s August, he/she may not want you to start the new dose and quantity regimen until then.