Not all members of a Work Group will start to consider the Implied Requirements of a piece of work at the same time. Unpredictable circumstances lead individuals to work through their portions of the Work Queue at different rates. Although any members efforts should be considered a contribution, the first to the problem may seem to others to have inappropriate influence over decisions effecting others.
Therefore: Assemble the whole Work Group as soon as one member begins to consider any part of the Implied Requirement. Consider the expressed needs and desires, the individuals who hold them, and likely strategies to meet them.
This is the beginning of the Development Episode and is a good time to sketch the first Informal Work Plan. This can lead to adjustments in group membership. It is also a good place for CRC level design.