onAfterRender of ui.toggle, Events Webix Docs

occurs immediately after the component has been rendered.

void onAfterRender();

some.attachEvent("onAfterRender", function(){
    //... some code here ... 
});

Details

The event fires each time the component is redrawn, not only after the component has been created.

To catch the moment of creation, supply it with webix.once() helper:

some.attachEvent("onAfterRender", webix.once(function(){ 
    console.log('called once after first rendering:'); 
}));