I would say there's no blanket answer here, because it all depends on context: how was the land farmed previously? There are conventional farmers who are doing a great job with soil health - Gabe Brown in North Dakota and Dave Brandt in Ohio come to mind. Their land would convert to organic beautifully. On the other hand, if the land was in continuous corn with yearly applications of anhydrous ammonia, lots of herbicides, and neonic seed treatments it might be more of an uphill journey. If the land was last treated with ag chemicals in 2017, most will have been inactivated by now, although if they used atrazine there might still be an issue with herbicide carryover. I would try to get as much information as possible about previous inputs, and if there's a well for the water supply, get that tested for minerals and bacteria, with a nitrate test as an add-on if that's not included in the standard package. And if there's a history of lots of atrazine usage, test the well for that also, since it's persistent and moves in groundwater.