I agree that you can build a facility to put energy on the grid in under a decade, but the probability that it works is going to be tiny, and anyone giving you the billion or so it would take would be disappointed to say the least.

Therefore, most credible folks are talking a 2-3 facility staged approach. And probably 5 years per facility to build, and 5 years per to test.

Also, remember that even with huge cash pools, you have supply chain problems. Some of the nonlinear optics takes a fixed amount of time to fabricate.