Deductions & credits

I guess I forgot to mention that I'm not an employee. I'm a small business owner so mileage driving to meet a client at a temporary workplace is tax deductible, correct? 

 

I guess my question is- can I start counting my mileage from home or must I start counting my mileage after I drop my son off to daycare which is on the way to my temporary work location?

 

Thanks for your help!