"Big bang" is a metaphor for the cosmological theory of the same name, in which the start of the cosmos happened at one moment in time.
The actual selection is done by prioritizing the goals to be achieved and then matching a strategy against it (Eason, 1988).
Parallel and phased introductions might help to control these risks, depending on the situation.
The actual selection of adoption strategy depends on far more factors then these goals, but they create a window to choose one of the types.
Based on table 1 and on the mentioned higher level variables by Gallivan, one can make a selection of an appropriate strategy to choose.
So now the test-phase can be prepared, in which the validity of the data that will be used will be checked and in which trials will be held (Eason, 1988).
This plan should consider all pre- and post- system rollout communications; user training & documentation; any internal marketing efforts that will be undertaken to drive adoption such as system branding or swag; as well as troubleshooting assistance during the rollout (i.e. extended help desk hours and/or a hotline, and identification of key contacts for each affected business area).