See connected device log on iTunes?
In researching this there does not appear to be any logs or details within iTunes that will show a list of devices that have been connected to iTunes. You can view the list of devices associated with the AppleID account and the list of devices associated with iTunes and that's about it.

Guidances from Apple on this:


  You can have ten devices (no more than five of them computers)
  associated with your Apple ID and iTunes at one time.


And this:


  The list of associated devices that you can view in iTunes is not
  the same as the list of devices that you're currently signed in to
  with your Apple ID. You can check your Apple ID device list to see
  where you're signed in on your Apple ID account page.
  
  You don't need to associate your devices to buy content or download
  new purchases. You can remove an associated device if:
  
  
  You reach your limit of associations and want to add a new one.
  You can't download past purchases from the iTunes Store.
  You want to sell or give away an associated device.
  


References


View and remove your associated devices in iTunes