"All set" is one of several idiomatic expressions among English speakers that is used to indicate that an individual or situation is fully prepared to initiate or move forward. The casual term may be used in a number of settings, ranging from indicating that an individual is dressed and ready to go out for the evening to the completion of a work project that can now be implemented. In all its applications, "all set" means that everything is in order and the next logical step can now be taken with full confidence.
Generally, the use of this particular idiom indicates that all relevant factors are now in place and that it is time to move on to accomplishing whatever goal or activity is next in the sequence of events. For example, someone who must leave for work in the morning will take the time to shower and dress for the activity prior to leaving the house. Upon completion of the preparation time, the individual can be said to be all for work. In like manner, that same person will complete his or her tasks at the end of the workday, including preparing the work area for the coming day, and be all set to return home.
In terms of decision-making, "all set" may refer to the fact that after a prolonged period of discussion and weighing of several different courses of action, a final decision has been reached. At that point, the individual or group involved in the decision making process is all set, in that they have reached their goal of settling on a course of action and can now move forward with acting on that decision. As part of the preparation, the decision will often lead to the accumulation of the necessary tools and equipment to move forward, an activity that can begin once all the essential resources are in place.
In just about every situation, being all set is viewed as a positive status. The term implies that all necessary tasks leading up to a certain point have been successfully completed, all resources needed to move forward have been gathered, and that the timing is now right to get on with whatever activity will come next. Even in situations that may have some degree of fear or anxiety involved, such as having some type of medical procedure, being all set implies that the patient has made all reasonable preparation for the event and is ready to move forward, hopefully to a happy outcome.