Schedule Jenkins build periodically

Under Build Triggers - Build periodically - Schedule you can create a schedule (or multiple schedules) for Jenkins to build periodically or on a specific date/time.
It might be tests that should be run periodically (every morning for example) or a DB clean up Jenkins job or any other Jenkins job.
To set periodically scheduled Jenkins jobs you should use Configure - Build Triggers - Build periodically - Schedule

If you have many different Jenkins jobs that may need to be built periodically or by special schedules and limited resources I recommend to use H in every Jenkins schedule where it’s possible to avoid spikes.
Jenkins build periodically - examples
Build every hour:
H * * * *
Build every 20 minutes:
H/20 * * * *
Build every 20 minutes 2am to 11pm:
H/20 5-23 * * *
Build every 20 minutes, work time/days (8am-6pm, MON-FRI) only:
H/20 8-18 * * 1-5
Build every hour MON-WED and FRI only:
H * * * 1-3,5
Build every hour, weekends in April and December:
H * * 4,12 *
Build at 8.30am on July 4:
30 8 4 7 *
Jenkins schedule format
Jenkins schedule format is nothing but a cron schedule expression. It contains 5 fields
 ┌───────────── minute (0 - 59)
 │ ┌───────────── hour (0 - 23)
 │ │ ┌───────────── day of month (1 - 31)
 │ │ │ ┌───────────── month (1 - 12)
 │ │ │ │ ┌───────────── day of week (0 - 6) (Sunday to Saturday;
 │ │ │ │ │                                       7 is also Sunday on some systems)
 │ │ │ │ │
 │ │ │ │ │
 * * * * *  schedule command to execute
Jenkins build periodically - predefined aliases
Jenkins also supports predefined aliases to schedule build: @hourly, @daily, @weekly, @monthly, @midnight
Schedule Alias
Schedule Description
Schedule command
@hourly
Build every hour at the beginning of the hour
0 * * * *
@daily, @midnight
Build every day at midnight
0 0 * * *
@weekly
Build every week at midnight on Sunday morning
0 0 * * 0
@monthly
Build every month at midnight of the first day of the month
0 0 1 * *
Jenkins build periodically - multiple schedules
You can apply even more than one schedule for a Jenkins job.
For example you might have a regular schedule to build Jenkins periodically, let’s say we want to build periodically every work day’s like this
30 8 * * 1-5
Let’s assume we need to build Jenkins periodically every week before weekend starts.
30 16 * * 5
Now we can easily combine these two Jenkins schedules

30 8 * * 1-5
30 16 * * 5
Jenkins will build every work day at 8:30am and every week on Friday at 4:30pm