Not sure which calculator you used, but you'll never ROI with an RK-Box at $700. Use this one, it'll set you straight:
https://bitcoinwisdom.com/bitcoin/calculatorActually, you'll be mining for a pure loss(electricity costs more than mining costs) by December of this year alone with that miner.
Only way you'd ROI is if you have "free electricity", and you run the RK-Box until February of next year.
Only hope of ROI'ing this year, is if you get this miner for $1 per GH/s or $500 or less and have free electricity costs and cooling.
Or if have cheap electricity($0.10 or less) and you buy it for $300 or so, then you could conceivably ROI this year.
Otherwise, the harsh reality is there is no hope of ROI for home miners.
BUY AND HODL BTC if you don't gots more than 10 TH/s in miners and free or cheap electricity and cooling!