The update (an early version of which leaked last month) is in two parts – first a small package of just over a megabyte (which makes sure part 2 installs smoothly), then the big 551MB package.

HTC has not announced an official schedule for the other Butterfly units out there, including the HTC DROID DNA for Verizon, but with the HTC One it didn’t take long from the initial release to worldwide rollout.
Source: GSMArena