IIRC there are ways to greatly speed this up by selectively planting certain fast growing trees to attract certain birds that will poop all over your lawn thus planting certain seeds. Basically you skip the first two steps with free bird poop. I think it was an old rail siding in London somewhere... or something like that. They planted a single willow tree that attracted the birds and BOOM ~~head shot~~ habitat.
https://www.rhs.org.uk/shows-events/rhs-urban-show/urban-gardening/guerrilla-gardening
https://theanarchistlibrary.org/library/sylvia-wilde-a-forest-garden-primer