Hello @mahbub2020,
Thank you for the request and sorry for the delay in reply.
Please that we are aware about the issue and our developers are working on fixing. Additionally we are prepering some new features for the Date Picker.
Once they fix it and implement new features, we will inform you in the the plugin changelog here: https://docs.stylemixthemes.com/cost-calculator-builder/changelog-1/changelog
We apologize for any inconvenience it may cause.
Best regards,