what is the {start time} for {Catherine II of Russia} has {country of citizenship} as {Kingdom of Prussia} ?
On what date did Catherine II of Russia gain citizenship of Prussia?
When did Catherine II of Russia gain citizenship of Prussia?
SELECT ?v WHERE { ?f property:start_time ?v . resource:Catherine_the_Great property:country_of_citizenship ?f . ?f property:country_of_citizenship resource:Kingdom_of_Prussia }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q36450> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P27> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q27306> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q36450 p:P27 ?s . ?s ps:P27 wd:Q27306 . ?s pq:P580 ?value}