When they are old enough to be very clear on their demands, but still young enough not to care about aesthetics. And, rather than trying to impress people, you get to make a cake that looks like it was designed by a seven year old. Some of the other mums who haven’t seen that particular episode of Charlie & Lola were probably slightly appalled. I also got told off for cutting the slices for the kids too big. I’m still making this parenting thing up as I go along, but we’ve made it this far. Fuelled primarily by cake, admittedly.