Trying to straddle the line probably won't end up well.  

I would personally make sure that you hold for rental purposes for at least 24 months, which would straddle three income tax years.  

@Everett Yano  Insurance for some House hacks can be tricky because it straddles the personal lines/commercial lines market. 

Advisors often recommend 12 to 24 months, but in this case since she has lived there for so long, I would be more conservative and lean more toward the 24 month holding period, which would straddle three (3) income tax returns/periods.  

Yes, potential investments must pencil today but, in a market where one must often be OK with either marginal cash flow or straddling the fence until another down cycle (or crash), it's nice to be in tune with the trends you mentioned so that we may assess overall risk AND execute while reasonably planning for the inevitability of change.

We generally recommend 24 months (our opinion, we're more conservative than others), which would straddle three (3) income tax returns and provide really good proof that you intended to convert and hold for rental use.  

I would recommend holding for at least 24 months, which would straddle three (3) income tax returns to easily demonstrate intent to hold for investment. 

I straddling the threshold/fence!

The landscape here is interesting because we straddle the state line and renting properties on both sides have their ups and downs.  

Unfortunately it wasn’t built in a way that I cannot  subdivide the land because the house straddles the property line.