PP from 16:00 here. Great suggestions pp. I like your 10-minute idea - I may try that one too.
"When.... Then..." is MAGIC!! So much more effective than "If...Then.." It bypasses so many (potential) battles with both preschoolers and school-agers for me.
I think that is one of the best tricks of the trade have learned this year! I've also shared it with a few other parents and they have (also) been surprised by how much difference it has made in a moments that could have become battles.