You have to deal with disruption. No doubt. A typical problem might be that the kid just isn't conscious of things like homework assignments: laziness, or ASD? If laziness, then discipline should help. If ASD then discipline won't help, but therapy might. Knowing really helps.

Having the right diagnosis is important. Who wants to end up taking powerful medicines for the wrong condition?? Sure, if you have no diagnosis then you won't take the wrong meds either, but that's not a reason to avoid a diagnosis.