Can I activate light maps at a certain moment during gameplay?

I have a game (3D, top down) where the player moves along a 3D platform made out of cubes of different colours. At the beginning, my cubes are initiated at z = -20 (my camera can't see any of them), they lift to z = 0 at random speeds. (the player will see how the floor is "generated" from cubes). After we get the floor in place, my blocks will remain static, and that's why I am wondering if I can bake a light map for cubes in the final position, and during the gameplay using a direct light while cubes move to z0 and than switch from direct light(realtime) to my light map.