The "not-so-pretty-but-it-works" solution I have come across is exactly what you are hinting at yourself.

1. Create the Continuous job - have it be paused
2. Create a secondary "start job"-job - which is basically just that API call in a notebook or python file, on a Cron schedule
3. Create a third "stop job"-job. The flipside of the above - also scheduled
4. Cry a little that it took 3 jobs to achieve what one job should do on its own - but be happy it does what it is supposed to do.