[Lynne]

This is an example of what works for every fourth post when you have 25 posts per page:

<if condition="($post[postcount] -4) %25== 0">
</if>

So, adjust that for your own use. Change 4 to 1 for first post and 25 to whatever for the number of pages. I'd actually go look into finding that variable and use it instead, but that's just me.