Ouch, you bought your 1080ti at the worst timing. It will take years to reach ROI with that price.

Perhaps, since you only got 1 GPU for mining, why don't you start with Nicehash (that's the best place to start for newbies) to earn Bitcoins which can be used to buy another coin or cashout to buy your second GPU (secondhand).

However, $1,200 for a ($700) GPU is a bad deal.