Casting on different colors

I plan on starting a scarf with two color cable…
It says Cast on 2 in grey, 2 in white, 2 in grey and 2 white…etc…won’t there be spaces with so many different starts?

Yes. Unless you twine the colors around each other, which it should say how to in the pattern. For the CO row, you would have to weave the ends in anyway so you can anchor them together.