From what I understand, Disney has 30 days to excercise their ROFR option. I believe when I bought (and someone from TSS will correct this if I am wrong) that the day after it is submitted is Day 1.
For example, if it goes to Disney today, November 11th, then November 12th would be considered Day 1. What I am not 100% sure about is whether or not it is 30 calendar days or 30 business days. And, if something needs to be ameneded, I believe it starts all over again.