When would there be a 2017 election for moderators and how do nominations work?
Every year or so the Stack Exchange team checks in and asks the mods if we need more help with keeping up our modly presence. Unless the answer to that is 'yes', (or if there are other extenuating circumstances like mods resigning or we request an election explicitly), there won't be an election.
As for how nominations work, there will be an announcement post on Meta, so keep an eye out for that. It will link to the current election page where there is a lot of helpful info about the nomination and election process. For example, from the previous election's page:
In the nomination phase, any community member in good standing with more than 300 reputation may nominate themselves to be a community moderator.
Nominees are required to construct a small, freely editable introduction to describe why they might make a good community moderator.
You can also browse all the previous elections by viewing the page at: https://gaming.stackexchange.com/election/