Myelination timeline: At birth, the dorsal brainstem and posterior limb of the internal capsule are myelinated

-After a few months, the ventral brainstem and anterior limb of internal capsule myelinate, followed by cerebellar white matter and parietal and occipital white matter a few months later.

-18-24 months after birth: The frontal lobes myelinate 

-The frontal U fibers, in particular, are very slow to myelinate and some of the last structures overall to myelinate.