I am renovating my kitchen/bathroom/house. When does an electrician need to be there?

The Electrician needs to be present:

Before the renovation is started an electrician needs to disconnect all electrical accessories/switches/fittings
After the necessary old walls have been demolished but before wall sheets have been nailed on an electrician is required to install new wiring and cables
Then at the end an electrician is needed to fit off new switches/fittings