populating nid in a custom field When creating a new node, I need to populate/fill a custom field with a value of the current node's id. What hook should I use to fill my custom field with newly created nid ($node->nid)?

I tried to use hook_node_presave but it was NULL, currently I am thinking to use hook_node_insert but as documentation says : 


  after the node is inserted into the node table in the database,


Does that mean if I assign the new value to my custom field it will be/not be saved to database?
I guess I found a solution for this problem:

function mymodule_node_insert($node) {
  $node-&gt;field_custom_field['und'][0]['nid'] = $node-&gt;nid;
  node_save($node)
}


I saved the changes to database with node_save()