TheTDG will start with "less than municipal governance." The base electoral units of the TDG will be about 200 residents that would constitute a natural neighborhood. The neighbors would elect one of their own to represent them in TDG governance.
These local TDGs will merge with each other. Each time a merger is attempted, this improves the skills in TDG governance. As the local TDGs are gathered into bigger TDG umbrellas, some of these umbrellas will encompass geographical areas that mirror the current local governance. But rather than promote itself as an alternative local governance, the TDGs should put their energy towards merging with other TDGs from other counties, towns, and cities. This would form a regional TDG, which would then be the starting point toward a provincial (or state) TDG. Again, more skills in TDG governance will be earned.
Eventually the goal would be to have one TDG covering the entire nation.
At this point, the TDG will be fairly mature. It will have a good record of finding capable people as its political leaders and coming to some effective decisions. It will be obivous to many citizens that the TDG is better than the current system. It would only be natural to assume that the TDG is eventually going to assume responsibility and authority for governance.
There would likely be some referenda on the TDG. The legislatures--most of which earlier dismissed the TDG as impossible or seditious--would acquience to the will of the people and pass some laws to replace current electoral structures with TDG strutures. The TDG woull assume the position of governance, similar to one political party winning the election and taking over from another party. Except this time, the new people will be bringing in some advanced attitudes for governance.
Please note that the TDG is building itself up by not directly attacking the workings of the current system.
Chapter 6 in my book explains this process in more detail. I list four stages of TDG building.
Thanks for asking this great question.