Definitely wait, especially if you have a 4K TV and keep an eye on the Xbox stock thread in here too. It was in stock for a number of hours very recently at Argos, Currys and Amazon. Unlike the PS5, once it shows as in stock, it does not seem to go within minutes. Also bricks and mortar like GAME tend to post on their shop twitter accounts when they have stock so worth keeping an eye on that too, assuming you live near one.
Like fattakin says, the drops are very frequent now so I don't think it should take you much longer to secure one.