I am able to achieve this because of your suggestion: I have added two maven steps in pom.xml.
<plugin>
<groupId>net.serenity-bdd.maven.plugins</groupId>
<artifactId>serenity-maven-plugin</artifactId>
<version>${serenity.version}</version>
<executions>
<execution>
<id>serenity-reports</id>
<phase>post-integration-test</phase>
<goals>
<goal>aggregate</goal>
</goals>
<configuration>
<outputDirectory>A:/reports - ${current.time}</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
Second Step: Added timestamp plugin
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<executions>
<execution>
<id>current-time</id>
<phase>validate</phase>
<goals>
<goal>timestamp-property</goal>
</goals>
<configuration>
<name>current.time</name>
<pattern>dd-MM-yyyy_HH-mm-ss</pattern>
<timeZone>IST</timeZone>
</configuration>
</execution>
</executions>
</plugin>
Thank you for the help John.