Try setting autoflush to true. It's likely just being buffered and not written. As for the date not being printed you'll need to use a formatter to get date. Assuming the default configuration there should be a patter-formatter called PATTERN which will log the full timestamp.
Also note you can override the jboss.server.log.dir by setting the system property in the JAVA_OPTS. Or you can configure a custom path and use that in the relative-to.
James R. Perkins