3rd pack - Kobolds & Catacombs or Classic (Watch a friend quest)
4th pack - Journey to Un'Goro
5th pack - Journey to Un'Goro
6th pack - Witchwood
7th pack - Journey to Un'Goro
8th pack - Witchwood
9th pack - Knights of the Frozen Throne
10th pack - Kobolds & Catacombs
11th pack - Knights of the Frozen Throne (and Classic, through watch a friend quest)
12th pack - Kobolds & Catacombs
13th pack - Journey to Un'Goro
14th pack - Kobolds & Catacombs
15th pack - Knights of the Frozen Throne
16th pack - Kobolds & Catacombs
17th pack - Kobolds & Catacombs
18th pack - Knights of the Frozen Throne (not sure where this came from...just showed up as a new quest when I logged in for the second time today)
Also, as a reference for future events... I had three quests going into the event last night, one of which was a "play X paladin class cards" that I had worked on to be within 2 cards of completion. I created a deck that had a bunch of paladin secrets and 1-cost minions, and kicked off a game as soon as the event went live, and conceded as soon as I played the two cards. I did get the pack for that one and a replacement quest -- so it was possible to squeeze another pack out of the event.
Guessing now that the data dumped days are actually pity timers for Witchwood packs.
First two packs: Classic and WW. Not sure which one was first since I completed two quests at the same time. Got the notification for the classic pack right after the match though whereas I was only notified of the WW pack after I next logged in.