I think that's generally a good approach - a script is a simple and flexible solution.

I would hesitate, however, to recommend the applescript delay command, which has had the reputation of being a surprisingly voracious resource hog, and, depending on the OS X version, might conceivably impact the perfomance of OmniFocus and any other applications that are struggling to get by.

BSD sleep has always been a good citizen, so an alternative might be something like:

or


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