Start a repetable job without the delay

[nullndr]

I have a long running job (like 2 hours) that must be repeated every weekend but I must have the option to click a button and run it on demand.

From the docs this is no more possible:

Adding a job with the repeat option set will actually do two things immediately: create a Repeatable Job configuration, and schedule a regular delayed job for the job's first run. This first run will be scheduled "on the hour", that is if you create a job that repeats every 15 minutes at 4:07, the job will first run at 4:15, then 4:30, and so on.

How can I start the repeated job on demand?