It took us 2 years, but we sheet-mulched most of a 1/4-acre suburban plot, and this spring (year 3) we planted herbs, vegetables, and annual flowers from seed for the first time, with
zero additional soil amendments.
I wanted to have a baseline for the "least amount of outside inputs and work possible." We used
cardboard to smother the grass, with a layer of organic mulch over the top, in some areas leaf litter, and in other areas tree bark chips.
All of the
native plants, many of them food plants, are thriving. But the perennial/annual seed-starting has been a real mixed bag. Details here:
https://www.catintheflock.com/2020/08/information-is-good-even-if-the-results-are-not-spring-2020-growing-season-report-card.html
Just want to share our results for others who might be just starting out on the
permaculture journey! Next steps: improving long-term soil health, better growing conditions for the seeds next spring.