if you want them to follow, why not displace the keyframes for cubes 2, 3, 4, & 5 by 1...

so cube1 starts at 0.
cube 2 starts at 1.
cube 3 starts at 2.

and so on.

if they're going to follow the same path then they should naturally continue one after the other, correct?

if 1 frame isn't enough, try 2, 3, whatever it takes to achieve the desired result.