Well, You used foot mark instead of inch.
But anyway, judging from the picture, those fuzzy melons look like the size of what they sell at Asian market. I have never grown this type of squash/melon. But generaly, you can harvest and cook them when small. For example, in my Asian maket they sell baby shark fin melons all the time. The thing is that young ones do not have that chewy texture; they are more like squash. If I were you I woild pick one and cook, to see how it is.