There is a triple on the last update which might be used to consider time lags between Wikidata and WDQS. This time interval can be used to stop editing if there is an unacceptable time lag.
Thats a good question.
It could be user configurable?
This probably depends on the specific wikibase instance and query service that the integrator is being used against.
1 minute might be a good default for wikidata? For your own install it might make sense to have this less, 20 seconds perhaps (twice the polling time of the default updater)