ahhh......you noticed that there's no set schedule on what to do and when to do it huh? there's a reason for that. every single tank is different. there is no golden rule, so to speak. just as if you were to go to an aquarium forum and ask "when should i vacuum my gravel", you will get 100 different responses from 100 different people.

my advice, spot clean your tank on a daily basis. change your water weekly, daily if using a water bowl. remove non eaten food as soon as you can after they are finished eating. you'll build your own schedule over time. also, and most importantly, is watch your frog(s). they are your best indicator of the conditions in there

good luck and enjoy those little guys!!