Do not launch on Thanksgiving. Trust me. Delay until the week after.
Also you should know that Thanksgiving through New Years is by far the worst time of year to try and launch a new (consumer) product of any kind. Every single (consumer) product in the world fights a bloody battle for attention and sales this time of year. Every store, every brand and every product category will be filled with promotions and/or slightly new offerrings.
If you must launch during that window, what you're launching must be either a) fucking amazing itself or b) your fucking amazing at marketing to cut through all that noise.
This is slightly different for my app as it's only targeted at HN users, and my intention is not to make a living off it. Still I'd like to make sure it gets a fair chance to be noticed.
As a rule of thumb, from the launches I've seen and been close to, they are not make-or-break for a company/product. You might get a bit of buzz, you might have a TC or RWW article about you, but as I think of successful startups that I didn't personally know, I can remember only a few launch days.
The important factor is in one of two categories:
1) consumer app: the app produces a TON of value, and everyone tells the people they know (viral growth)
2) business app: viral growth is a factor, but there's probably going to be a lot of sales-y activity required.
Neither of these categories are largely dependent on a launch. A launch is more important when you've already got a ton of eyeballs.
Again, this is a rule of thumb, and I'm not aware of a single person who I would say is a true expert around launches.
What do you think?