Thez come directly in front of the infinitive. No one said to clean out the attic. No one told us to clean out the attic. It wasn't easy to clean out the attic. A notional subject differs from a true subject in that it can be anywhere in a sentence and its case doesn't matter.
Tall people find it easy to reach the pedals.
It is easy for tall people to reach the pedals. Marcia has to see the dean. It was important for Marcia to see the dean. It is important for them to arrive early. They think it important to arrive early.