When you add a smart field to a constituent record, the data pulled in is for the current member while a smart field on a household record looks at all revenue applied within the household. If you are looking at individual constituents in a query and pull in "first gift date" its the first gift date for the constituent, not anyone in the household. We've built a series of queries to get to the "true" first date but there must be a way to create a smart field, that can be added to the individual constituent record that reports 1) First gift amount of anyone in their the household, 2) First gift date of anyone in their household, etc.... That way we don't acknowledge a constituent as a "1st time giver" even though their household has been given for 25 years... embarrassing!