I'm guessing this is a conventional buy, so make sure you have and use your inspection contingency to check for it being an approved triplex, and make sure you have your financing contingency in case the appraisal comes in low.

Why do you feel this would be a better route than just 3 conventional loans?

& definitely, I plan on moving to conventional loans once I have more skin in the game and more wealth built up but FHA makes the most sense to me to get in the market quicker.

Hmmmm, considering the rate differential would be close to 4, on a conventional you could say over $4k a year that could go back into your property. 

The better and cleaner way to go is either get a temp loan (conventional, private, hard money, etc), do the repairs, then Refi the home into a conventional amortized loan.

When I first started the process I got preapproved for a conventional loan with 5% down.

For more conventional financing, you'll have to probably be in the high 600s or better.

Current home-owner now on a conventional loan.

I actually planned on using a conventional or home ready loan with low down payments to avoid PMI.

An optimal BRRRR really requires that you purchase with cash (or something cash-like) and not conventional financing.