I send the first email as early as possible. Then another one two weeks or more later (I have found some managers just don't reply to emails but they still end up doing what they have to do league-wise). Then one final one when its getting down to a week or so before things are happening (deadlines etc). After that they're in the red zone. If I don't hear from them in a few days I'll probably send an email saying I need to know otherwise I'll have to start looking for a new replacement, if you want out of the league LMK no hard feelings etc. About 24-48 hours after that I'll begin my search and make the manager change ASAP. I would also have a backup schedule for your league in mind in case someone bails last minute. One year I had a guy who didnt select his keepers by the deadline so we all had to push things back slightly.