There had been a previous attempt to reprint HQ that ended in massive lawsuits shortly before the Hasbro version was announced. So people were already somewhat aware of the possibility or HQ's return.
Hasbro/AH started a HQ twitter a few months before the main announcement. They put up a webpage with a countdown timer 10 days before.
Here's their announcement, at 1:25:
Here's the thread from the HQ forum, launch was 9/22/20:
http://forum.yeoldeinn.com/viewtopic.php?f=143&t=5381
The goal was in dollars, not backers, and the $99 level was a lot more accessible than $249. Looking at that thread, it hit 24% of its goal in the first hour. There are also people saying its too expensive.
Hasbro was showing all the pieces in greyscale for the first few weeks. They eventually showed different colored minis and furniture pieces that matched the original set, but it wasn't clear if that was the plan all along, or if they changed it due to request. They have showed Haslabs in greyscale at the beginning before, like the new Transformers one, which just passed HeroScape's backer count, in about two hours.