You have more options:
-
Create extractor with Copy Input with Date converter:
https://docs.graylog.org/en/3.1/pages/extractors.html#the-standard-date-converter -
Create extractor with Copy Input with Flexible date converter:
https://docs.graylog.org/en/3.1/pages/extractors.html#the-flexible-date-converter -
Create pipeline rule with correct datime format
https://docs.graylog.org/en/3.1/pages/pipelines/functions.html#parse-date
Please send your example of your actual timestamp and desired