Vaadin UI done or documentReady event

Is there any way to detect all Vaadin components, html, elements are loaded and rendered in UI.
After this i want to push something to UI.

Vaadin version: 8.0.5, spring boot 1.5.2

i see in dev mode in browser console if all done:

... com.vaadin.client.communication.MessageHandler
INFO: Referenced paintables: ...