It will take about a year I guess, to mine 3.9BTC with the S4+.
Could be a bit earlyer but I guess about 10 months.
It's up to you and me if we going to take the gamble if we think the price will gain alot or not.
You won't make it if you factor electricity cost and all the work you'll put into this crap.
Just buy 3.9BTC with the money you are going to spend on that machien and hold these BTC. You'll end up with more BTC (3.9 instead of 1,2 or maybe 3).