These time cubes are one of my favorite tools to help with the executive function challenge of Task Initiation. Getting started on something you DON'T want to do is hard for everyone. Think: taxes (ugh), cleaning a gross cabinet, homework...
It's also helpful when you want to limit breaks that turn into 30-40-50 minute stretches. Turn over a time cube for 5 minutes and when it goes off, you'll be reminded to get back to work.