Best days to visit during dec 12 - 18?

[LSUwest]

Hi,

We will be staying at WDW from Sunday Dec 11th to Monday Dec 19th. During that time, we'd like to visit IoA and US for 2 days. Can anyone recommend which 2 consecutive days would be best to visit them? Really just concerned about crowd size plus anything else we may not be aware off. We've been to WDW a few times, but never to IoA/US.

Thanks