What time line makes the most sense?
Here isa feeble first effort at a possible time line. Once the project gets going, the leaders will replace this with better and better estimates.
2000 - 2020
Live through the ridicule and condescension of the experts as one after another "proves" that thrusters cannot do the things we think they might. Meanwhile, climatologists begin to model some of the possibilities that thrusters might provide. Organizations in the fossil fuel industries begin supporting the project in hopes of providing an alternative to proposed restrictions placed on fossil fuels if the global warming debate intensifies. Geologists argue that the weather patterns of history have nothing to do with asteroid strikes or mantle spins. Ice age experts will continue to argue that ice ages aren't caused by close calls with humongous space objects that threw the earth out of orbit for a while, or changed the tilt for a while. Scientists of every kind will begin to examine their science for the possibility that various forces have acted on the earth in the past and its tilt, orientation, orbit, might have varied in the past.
Examine and debate the various creative proposals that show that maybe thrusters could work after all. Subject every new proposal to peer review. Take some years to give the various sciences a chance to examine the various proposals to see which would accomplish the most benefit for the least risk and cost.
Begin to gather the support and cooperation of the multinational corporations as they start to see the possibility of success. Begin to build relations with the governments of the world so they can see the benefit of cooperating and supporting the project.
Build a variety of test thrusters of different sizes, fuels, and methods. Find ways to test the devices to determine the effective thrusts of each. Work to build scientific consensus on which systems, patterns, fuels, and control systems are best.
Install thrusters around the world as needed to achieve the various goals.
Subject the alternative climatology programs to peer review and achieve consensus on the assumptions. Make the first test of the system. For example, reduce the tilt by one degree. Then move it back. Proof of concept and proof of predictability will be the goals.
Make training modules available on the web for every aspect of the project, in every language deemed necessary. Create tests that confirm learning, awareness, and applicability of the concepts taught. Begin to test and certify the informed citizens who will vote on the initiatives proposed by the board of leaders. Prove the security of the voting process so each person's voting privacy is protected guaranteeing anonymity. And prove the security of the voting process to assure that the ballot box cannot be stuffed.
If none of the potential dangers recognized today have required action, begin examining various proposals for improving the quality of life on earth, and its productivity in terms of crops to feed the potentially huge population.
If a majority of the earth's voting citizens approve a proposal, implement it.
If a majority of the earth's qualified voters do not support proposals, improve the science, reduce the risks, enrich the benefits, until consensus can be reached for life enhancing initiatives.