Ask HN: What is the best day to announce new feature?

In my experience, it doesn't really matter. However, one suggestion I do have is to roll out the feature to a beta group first. I manage a bunch of products at my company, one of them which has ~400 unique visitors per day using it. I typically roll it out to a group of 10 of the power users that I have a direct line of communication with. They vet the new features over a few days and give me feedback. I know they won't leave the service because of a bad bug, so it's worth it to let them throw a bunch of use at it (that you often times don't think of when making the feature).

I saw something recently that said Tuesday. Lemme try to find it.

Got it: http://philosophically.com/dont-launch-your-product

I would argue that isn't really relevant in this case. They have a working product and are announcing new features. The linked article is pretty different.

Don't release it on a Friday unless you're willing to give up your Saturday to fix bugs