what is the {start time} for {Julie Andrews} has {spouse} as {Tony Walton} ?
At what time did Tony Walton become the husband of Julie Andrews?
When did Tony Walton become the spouse of Julie Andrews?
SELECT ?q WHERE { ?u property:spouse resource:Tony_Walton . resource:Julie_Andrews property:spouse ?u . ?u property:start_time ?q }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q161819> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P26> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q2803671> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q161819 p:P26 ?s . ?s ps:P26 wd:Q2803671 . ?s pq:P580 ?value}