If you've been tracking the rental in TurboTax and have been using a desktop version, then open up your 2016 income tax return, save it immediately using a different name, e.g. add "Rental Sale" to the original name, and "sell" the rental in your 2016 income tax return. While you're in there you can make any other material changes that you know of - big salary increase?, inherited money and put it in dividend paying stocks?, something else? - and see if you're assessed a penalty. If not you're probably OK. If you are assessed a penalty you could either increase withholding for the balance of the year, or make estimated tax payments.
