When does Office 365 Groups recalculate expiration date? After changing Group lifetime days to 365

Hello,

Can someone help me answer the below question.

When we change the expiration days in Azure for Groups from let's say 450 days to 250 days. When does it start sending emails to inactive groups, as we have reduced the days to 250. I saw Microsoft document that says, 'It always starts counting from the date when the group was created, and then applies the new expiration policy'. But question is specific after how many days does it start sending email to inactive group with no activity in past 250 days. 

I made change to days from 450 to 250 and it has been 16 hours but not seeing any emails going to inactive group Owners.