It is a great ability to read ahead on any piece on any instrument but it is a talent that takes a long time to refine.
The first step to doing this is to learn how to play without looking at what your hands and feet are doing, this will mean that your eyes are always able to be on the sheet music. To learn this, try to get (or make) some extremely simple sheet music where all successive notes are one or two tones distance from each other. Don't worry about timing at this point but just try to play the next note by feeling where the keys are then check if it was right. Eventually remember the whole bar and play the piece in the right time signature at different speeds in different keys.
When you have mastered the above try to memorise a whole bar, while playing this first bar slowly, look at the next bar and try to memorise as many notes as you can. Play the piece slow enough and try to even use a metronome until you can remember the first bar while reading and remembering the next bar. At this point you can play the second bar and read and remember the third bar and so on. At this point speed up the process and increase tempo and complexity of pieces you do this with. Don't ever think that you need to go the tempo of the original piece all the time but start at a manageable tempo and then increase it until you have reached the desired tempo.
To initially learn this process, which I still haven't mastered due to a lack of practice and motivation, I created a couple of sheets of one handed sheet music where there was one note per bar. I got to the point where I could play this at a significant tempo and memorise two to three notes ahead.
Good luck in this learning process!