Instagram launched web profiles, and they're in the process of rolling them out to all users over the next week.
That annoys me. If you're launching something on the web, I think that you should do whatever you can to make the change as close to instaneous as possible: Your profile didn't exist, but now it does. We just launched it. Go check it out.
That's the ideal case. DNS propagation will complicate that a bit, but that's a far cry from what we see here. Here's a roll out that is taking a week or so to be available to all users. That sucks. It creates inequality and sows confusion among users.
Instead, I believe that great pains should be taken to avoid the above. Build the pages, the databases, the images. Store them, link them all up, and then push them live. Because your best users are going to be excited by the newest thing you've done, and when they don't have it they're going to be disappointed. I'd rather see you launch a week later with happy users.