Unless you have set up your engagement program to have leads added to streams based on their region and set the casts based on the region the majority of the leads are in, there currently isn't a way to do this. There is an idea on the community to have emails sent based on the lead's time zone: Send emails based on local times
As Val said, you may want to set up your nurture streams based on region if this is important to you. I know this is a pretty common setup for international, etc.
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