When can we expect to receive the OTA software update to Marshmallow?
My phone's unlocked and was not purchased through Fido.
Anybody has any insights?
The OTA (Over the Air) update has started rolling this week for Nexus phones, and Google doesn't update every phone all at once, so it could take a week or two, assuming no major issue turns up in the update.
If you can't wait and know what you're doing, you can find either your phone's image here or the update here. If you don't know how to manually install those update, however, you're probably best to wait until the update arrives through the normal channels.