EL Expression in Announcements how to use with date of hire plus 30 days?

Summary

EL Expression in Announcements how to use with date of hire plus 30 days?

Content

Hello,

We would like to use EL Expression , in the Announcements(under Tools) the one that is enabled by personalization from the appearance . 

we would like to have it being displayed ONLY 30 days after the hire date of the employee.
I checked in the EL EXPRESSIONS possible how to get the hire date of the user. 
#{webCenterProfile[securityContext.userName].dateofHire}

Question - how can we check in th expression if 30 days has passed ? how can we use numbers to the date ? 

Thanks a lot