There is a good treatment in The Martian, where he uses his own night soil and composting all organic waste. With geometric growth it will cover "land" in short order, given water and labor to spread, mix, and prepare. (Weir's characters all refer to all dead regolith/crushed rock as "soil" too, which bugs me).
Heinlein's Farmer in the Sky describes the work of doing that on a holmstead-sized scale.
What's your friend have against it? It might be just fine in a closed planting box. It also doesn't need to be self-sufficient as an ecosystem, just allow the plant roots to work. Plants can be grown hydroponicly, so a large planter is possible.
In general, you want to carefully prepare both the microbiome and other self-replicating agents that extract power and resources in situ while doing the task of mixing and spreading further. E.g. earthworms, grubs, and various bugs.
Given crushed mineral matrix as a pre-existing starting point, you need to add water and inoculate the biome. If optimally mixed/layered/tended it will double in a few days, and you can divide that and repeat.
Using plots larger than you can tend explicitly, you want a small, patch to grow outward, which will be less efficient moving from soil to plain rock and only along the border which is growing linearly not geometrically.
So you improve it two ways: transplant into new disjoint patches as much as you can, and somehow coax it to spread in a fractal pattern.
RAH's farmers made stripes which grew together. How about controlling the irrigation to lead the growth in a pattern? Also engineer the "bugs" to cause dispersion to new areas.
Back to your friend's objections regarding the time scale and input. First, you are a well-prepared mission not a castaway with nothing but his own poop and one living plant. You can have a complex mix, multiple different mixes for different stages, and even engineered species.
The difference between "big pot" and "self-regulating ecosystem" is not all or nothing. For good story, you can imagine managing the degree of hands-on regulation needed vs. the size that can be handled with available labor and logistics.
Amending the soil while plowing and planting, adding fertilizer to irrigation, and weeding and checking pests, is all normal in agriculture which is more productive than nature. If you can add stuff— nutrients or new bacteria and fungi— to the irrigation water, you can easily give it whatever it needs on a day-to-day basis. So maybe you don't need anything more than crushed stone, essentially doing hydroponics on the ground.