AD get when created and last Changed

$DateCutOff=(Get-Date).AddDays(-30)

When Created

Get-ADUser -Filter * -Property whenCreated | Where {$_.whenCreated -gt $datecutoff} | FT Name, whenCreated -Autosize

When Changed

Get-ADUser -Filter * -Property whenChanged | Where {$_.whenChanged -gt $datecutoff} | FT Name, whenChanged -Autosize