Workflow move item to another list with name variable

I need create a workflow that move all items in a list to another list. This is easy. But I need that the name of the second list be the month and the year. I create a script that create the list automatically but i dont know how to make it take the name of a varible. Any idea?

Thanks!

This is the script used to create the new list.

$site = Get-SPSite siteserver 
$web = get-spweb -Identity siteserver/site 
$xd = Get-Date -Format MMyyyy 
$listTemplates = $site.GetCustomListTemplates($web) 
if ((Get-Date).day -eq 1) 
      {     
      $web.Lists.Add("$xd", "", $listTemplates["Archive_List"]) 
      $spList = $Web.GetList("siteserver/site/Lists/$xd/") 
      $spList.OnQuickLaunch = "True" $spList.Update() 
      }