I’ve released a v1.1 which adds Timestamping capabilities, using https://timestamp.geotrust.com/tsa Time Stamping Authority.
It is optional because this will add an extra call to the URL, and thus require internet access and adds a little bit of time to the signing process, so it is not activated by default, but you can check the ‘Use TSA’ in the preferences to activate it.
You can also provide another TSA URL in the preferences, just note that the Timestamp server must comply with the RFC 3161 protocol and that the TSA must be one of JRE’s trusted roots CA (usually your certificate provider should be able to provide you with a TSA URL).