How to get the Date, when particular field of a node is equal to some value?
You have to use one of the events described in Entity CRUD, editing, and view hooks.

One example from the documentation:

function hook_ENTITY_TYPE_update(Drupal\Core\Entity\EntityInterface $entity) {
  // Update the entity's entry in a fictional table of this type of entity.
  db_update('example_entity')
    -&gt;fields([
      'updated' =&gt; REQUEST_TIME,
    ])
    -&gt;condition('id', $entity-&gt;id())
    -&gt;execute();
}


You can get the original field values from $entity-&gt;original-&gt;status and check if the status has changed.