Goal is to try to delay any watering on Friday morning (if scheduled) so as the lawn service can mow the lawn.
Am thinking about IFTTT recipes. Here are my two thoughts:
Pause/Resume IFTTT triggers. Will resume continue where we left off in watering cycle when we paused?
Rain delay: delay for 1 day. Question is if there is a Friday delay, will there now be a Sat 5am watering?
Any other suggestions
I am deprecating these, as they are not supported in mobile or web.
The rain delay will not run the schedule on Saturday.
We currently do not support a 6 hour delay. Best bet might be to rain delay for Friday, after lawn service you can just manually run the schedule.
Flex schedules coming out Monday allow you to opt-in to watering days. So, you could essentially opt-in to M-Th, Sa, Su and let flex take over 
Your flex scheduling suggestion sounds like a more elegant solution. Thanks.
Hide you wife and kids, dey be flexin ppl out hea.