I was told that you have to pay PMI for 2 years even if the LTV is at 80%. I was also told it was 78% LTV. You might want to confirm with a loan officer just so you aren’t disappointed with all of the FHA rules.
Personally, I don’t like that you can’t waive escrow on FHA so you will have taxes and insurance included in your monthly payment. I would rather keep the cash and pay it every 6 months.