I always saw this picture labeled as Olga first communion, but I have to admit you’re right it could be Easter, because the Orthodox Church doesn’t celebrate a first communion. I belong to the Orthodox Church (Greek Orthodox) and I never nor any of my relatives had what it is called a “first communion” as Greek Orthodox we don’t celebrate it here, though other non orthodox Christians communities in my country (I’m from Lebanon) still somehow give the first communion its importance. And looking at the picture, the event seems more important than a first communion, in Orthodox faith Easter is regarded as the central day in the entire Christian calendar (religiously speaking it is more important than Christmas in Orthodox Church).