Hey

1) Electrical conduit pipe, fan hook, light point should be laid at the time of laying RCC slab.
2) All electrical boxes, electrical conduit pipes and other points should be fixed into the wall before plastering.
3) Electrical wiring should be done when the plaster is dried before starting painting and white washing.
4) You should use good quality ISI mark best material (best quality cable and switches) available in the market and should be purchased from reputed firms.

Thanks