How Long After Taking 10mg Adderol Can Its Effects Be Felt?

I've just taken a prescribed adderol (generic amphetamine salt) and have waited 1 hour and feel no effect. My doctor told me to play with my dosage and figure out what works best but I want to know how long after taking 1 10mg dose of amphetamine salts can I start taking more until I feel some effect. For the purposes of figuring out my dosage.