What will I notice in a 6 year old starting adder all XR 5 mg?

Change in attitude. Most 6 year olds can't swallow a pill, so that will be an adventure. Assuming they take it, you will see a fairly dramatic change in behavior and attention within 1-2 hours. Again, assuming the correct diagnosis is made, a better ability to stay on task, less impulsivity. There could be some mild stomach ache and decreased eating too.
It depends... Depends on the reason for the rx; depends on whether this med &this dose are right for this child; even if dose/med is ok, child may not adjust to it right away. There r so many factors & considerations here.Hopefully, you'll see more self-control, better behavior, improved performance, better social interactions. You may get some or all of these & also get "rebound", low appetite, sleep problem.
Depends on ADHD type. The effect of Adderall (dextroamphetamine and racemic amphetamine) XR depends on the type of ADHD your child has. If he is hyperactive, you should see him calm down and be better able to focus on tasks and be less impulsive. If the problem is inattentiveness, improved attention and focus should evident.