As a 'bottom up' interviewer, I'm often criticized for the same approach you're taking. You might do well to start at the highest level (and pseudo code) and w

As a 'bottom up' interviewer, I'm often criticized for the same approach you're taking. You might do well to start at the highest level (and pseudo code) and work your way down to the clock. In fact, I'd start with bad examples of temporal messaging and work down from there: ("Debit 250", to "Debit account A 250", to "Debit account A for 250 at timestamp Y", to "Debit account A for 250 at signed timestamp Y") -- showing bad is often more effective than explaining good.