It is often the case with recipes written for those new to cooking that directions need to be given for basic things like telling when something is done or not.
A cake is done when the Maillard reaction has taken place and the proteins surrounding air pockets created by leavening have solidified. Or, in other words, it looks edible and when pressed gently, bounces back.
A chicken is done when the skin looks crisp, the leg is wont to pull away from the body with ease, and if you’re really not sure, the fluids released from a skewer poked deep into the side run clear. Or if it’s been in there about an hour and a half, for a normal-size roasting bird.
Rice is done when it has absorbed all the water and fluffed up to three times its size.
Some things are more ephemeral or are determined by personal preference.
A steak, for example, might look well done on the outside but remain rare inside — only a flesh firmness test (an experience) will tell you for sure.
A boiled egg looks the same as an unboiled on the outside but behaves differently when rocked and dropped. A sure sign it is no longer raw: if it’s been in hot water for ten minutes. An egg that has boiled too long will let you know by exploding.
This recipe’s directions are charmingly casual yet helpfully specific: pouring the egg into a hole which reveals the pan’s surface will cook it in a way that simply adding it to the rice mixture won’t.
And “when it looks finished, it is.”