what is the {start time} for {Judah P. Benjamin} has {position held} as {United States senator} ?
When did Judah P. Benjamin begin serving as US senator?
When Judah P. Benjamin started his position as United States senator?
SELECT ?h WHERE { ?r property:position_held resource:United States senator . ?r property:start_time ?h . resource:Judah_P._Benjamin property:position_held ?r }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q466115> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P39> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q13217683> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q466115 p:P39 ?s . ?s ps:P39 wd:Q13217683 . ?s pq:P580 ?value}