Add panelizer display when create a node programmatically
Here is some example code for creating a node and setting the panelizer variant/display automatically.
Note: The EntityMetadataWrapper module is used for setting the title.

  $entity_type = 'node';
  $bundle = 'page';
  $variant = 'YOUR_VARIANT_NAME';
  $variant_name = $entity_type . ":" . $bundle . ":" . $variant;

  $values = array(
    'type' =&gt; $bundle,
    'uid' =&gt; 0,
    'status' =&gt; 1,
    'comment' =&gt; 0,
    'promote' =&gt; 0,
  );

  $entity = entity_create($entity_type, $values);

  ctools_include('export');

  $panelizer = ctools_export_load_object('panelizer_defaults', 'names', array($variant_name));
  $entity-&gt;panelizer['page_manager'] = $panelizer[$variant_name];

  $wrapper = entity_metadata_wrapper('node', $entity);
  $wrapper-&gt;title-&gt;set('Your Title');

  $wrapper-&gt;save();