Candidates

There are several candidates from common ontologies:

Wikidata

In Wikidata, the properties P580 (start time) and P582 (start time) are used for exactly this purpose. For an example see e.g. statement on spouse of Douglas Adams.

Dublin Core Terms

The Dublin Core Terms vocabulary provides dcterms:valid to state a date range of validity of something. However, it is not clearly defined how to represent the date range. As there is no xsd datatype for date ranges, one could think of

1. time:ProperInterval with time:hasBeginning and time:hasEnd both pointing to a time:Instant wiht time:inXSDDate.
2. rdf:List with two xsd:date, or
3. simple xsd:string. But all would be complicated to query.

schema.org

Schema.org provides schema:startDate and schema:endDate. Using them for the validity of statements would be similar to their intendet use for the validity of Roles.

Anti-Candidates

On the other hand, there are also some properties, that might seem to fit on a first sight, but thous definition is not compatible to this use case:

• Provenance Ontology: prov:generatedAtTime and prov:invalidatedAtTime

This is probably not complete …

Using the RDF Reification Vocabulary for this use case is perfectly fine. But you might also want to have a look into the new reification mechanism in the upcomming RDF 1.2.