I would like to have script that checks for specific user that this user has set in his user preferences that after login to Jira what sees the first is own dashboard ("MY JIRA HOME = DASHBOARD") and if this is not set, set it.
Please see screenshot in attachement.
When new people first log into Jira, they will land on the system dashboard.
It is rare for people to change that until they've learned enough about using Jira to understand what they're doing with the defaults.
You should design a simple, and guiding, system dashboard, instead of overwriting settings which people probably haven't yet changed.