Maintenance for the week of December 1:
• PC/Mac: No maintenance – December 1
• NA megaservers for patch maintenance – December 3, 3:00AM EST (8:00 UTC) - 12:00PM EST (17:00 UTC)
• EU megaservers for patch maintenance – December 3, 8:00 UTC (3:00AM EST) - 17:00 UTC (12:00PM EST)
The list that I've been referencing is this one. The author has been doing a good job of keeping it up to date.
In general, if a set has no condition (other than the number of set pieces) associated with it, it will always work. If it does have a condition, then you'll need to look at the list I sent above or the original patch notes.