Well if you're interested I'd still get the reservation in today, it's only going to get worse when "the general public" gets access to the reservations tomorrow.
And depending on where you live it might also still be Q1 2021.
Just check what it says here for you:
Steam Deck™ is the most powerful, full-featured gaming handheld in the world.
store.steampowered.com
(I also secretly hope that this is just the absolute worst case, since I imagine a bunch of people will eventually cancel and you'll move up the queue, or Valve is going to produce more or it's just a
really conservative estimate.)
It's just a refundable 5$ deposit, might as well.