Your clowns are only small and I think the general consensus is when fish are juveniles that they are fed more often.
Two small feeds twice per day or one decent feed per day would probably be the way to go, and maybe skip one day per week altogether. It's good for fish to completely empty their digestive tracts regularly, but personally I think your planned feeding regime of three times per week is probably a bit wimpy at this time, given their size. Mine get fed 3 or 4 times a week but they are all between 5 and 7 year old, biggest around 7".
The best way by far to determine whether your fish are getting enough food is to simply observe them. Fish that tend not to get a lot of food have that skinny "pinched" look around their shoulders and obviously the sunken belly look too.
If they look ok and are very active, as clowns tend to be, then I wouldn't worry too much. DO NOT use their glass surfing antics as a sign that they're hungry. It's the craftiest trick in the fish play book, lol.