Android Wear 2.0 has been put on hold for many watches due to a bug, but apparently the Polar M600 watch isn't affected. The official Twitter account for Polar has confirmed that the update is now rolling out to the M600, and will take up to a week for all devices to get it.
Starting today, the update will roll out gradually within the next week. M600 will notify you automatically :)
— Polar (@PolarGlobal) March 30, 2017
The Polar M600 is one of many watches confirmed to receive the Android Wear 2.0 update, so this shouldn't come as too much of a surprise. Hopefully the rollout will start for more watches soon.