https://medixway.com/adhd/adderall-12-5-mg/

Doctors will usually start an Adderall dosage at the smallest amount that may potentially work and then gradually increase it. For ADHD, the immediate-release dosage for adults is between 5 mg to 40 mg a day. The dosage is divided throughout the day. Adderall extended-release (XR) can take about 30 to 60 minutes to start working, and it lasts for around 10 to 12 hours. Both IR and XR can lead to a crash as someone comes down from the effects of the drug, but XR tends to have less noticeable effects.