By default, the CCK date field was in the following format.
- CCK 2011-10-01T00:00:00
You can get the timestamp from the above the string by the the PHP the strtotime() function.
<?php $node = node_load($nid); $timestamp = strtotime($node->field_cck_date['value']); print $timestamp; ?>
Reference: Return Unix timestamp from CCK date field