How exactly does GOTW work?

I have been trying to nominate a candidate for several weeks, but have not been able to so far. Was the time for nominating candidates shortened? The time available is not clear at all. Is there a maximum number of candidates?

Suggestions:

• Clearly show the remaining time (in hours) to be able to propose candidates.
• Limit the number of times a user can propose candidates. For example, the same user cannot propose candidates two weeks one after another.

The nomination starts exactly when the new GotW is selected, which is done by a script at a set time. You can see the exact time by hovering over the time in "will be selected X days from now" on the GotW page. Currently it's set to 08:00 (am) UTC on Sunday, which is a recent change. It was 17:00 UTC on Sundays for a long time.

The nomination ends after 15 choices have been submitted, and then voting begins. I think this usually happens within at most a few hours after nomination has begun.

I like the idea of switching to nomination lasting a set amount of time, rather than until a set number of choices has been reached. This would run into issues if GWM happens to have a longer outage on the nomination day, though. An alternative would be to increase the number of choices required until nomination ends.