Concrete should be screeded as soon as it is poured into the site. Typically, one operator is using a rake or shovel to spread the concrete into place and another operator is using a screed to smooth the surface after them. The vibratory screed should be used slowly, so that every part of the concrete is vibrated and smoothed. You will know the concrete is properly screeded when there are no cracks or bumps and there is a shiny film of water on the top.