what is the {start time} for {Walgreens} has {chairperson} as {Charles Rudolph Walgreen, Sr.} ?
When did Charles Rudolph Walgreen Sr, the chairperson for Walgreens start?
When will the chairperson for Walgreens, Charles Rudolph Walgreen, Sr., start?
SELECT ?p WHERE { ?s property:chairperson resource:Charles_Rudolph_Walgreen,_Sr. . ?s property:start_time ?p . resource:Walgreens property:chairperson ?s }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q1591889> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P488> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q5082215> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q1591889 p:P488 ?s . ?s ps:P488 wd:Q5082215 . ?s pq:P580 ?value}