Settings -> Interval -> [Set up the desired interval]
I usually use 1440 on my sites (24h), but it depends on the number of the pages on the site. If for some sites it takes more than 24h to warm (big depth setup and many pages on the site), then it’s wiser to set the greater interval (48h etc).
Anyway, only 1 warming can run at a time, so if you have a long warm-up running and another one scheduled at the current time, the scheduled one will be silently skipped.
I think we will add some table in the future so that you could see which intervals were skipped because the other warm-up was running.