A Delphi survey takes several weeks, even if the number of participants is small.
It has to be planned in the beginning of the project or, if the necessity to conduct such a study appears late in the course of the project, it is important to realize that the whole process takes several weeks, depending on the number of rounds needed. The next figure illustrates the whole process and the time needed.
Figure 5 – The Delphi process
Adapted from Slocum et al93