how to set time in jenkins

2. Build Triggers
We specify how often we run those tests.
we choose Build periodically because we
want to run in certain schedule. 
in my project, we run smoke tests every morning.
so in the build trigger we entered daily option:
H 6 * * * --> every day around 6 am.
Jenkins used a cron expression, and the different fields are:

  H * * * *   ==> Build every hour at any minute (6.12 am, 8.38pm)
  0 * * * *   ==> Build every hour at exactly on the hour (6.00 am, 8.00pm)
  0 8 * * *   ==> Build every day exactly 8.00 am
  H/5 * * * * ==> Build every 5 minutes
  H 6 * * 1-5 ==> Build around 6 am from first day of the week (Monday) to 5th day (Friday)
  H 1 * 6,20 * * ==> Build on 6th and 20th day of the month around 1 am for regression