[Shishir]

Don't know if it helps you but here is something you might try.

First, open 'postbit'(or 'postbit_legacy' whichever you use) for edit. Look for:

$post[postdate]<if condition="!$show['detailedtime']">, $post[posttime]

Add Before:

<if condition="!in_array($post[postid], array(number1,number2,etc,etc))">

In the same line find:

</if>

Add after:

</if>

Replace the number1,number2,etc,etc with the Post ID you want date and time to hide.

Hope it helps.
Shishir