All the dealerships have allocation for the retail side on GTI/GTD orders, fleet sales are less restricted - which is where most of the broker cars come from.
For an average sized dealership they're allowed 1 a month of each (that might ease offonce we get rid of the initial rush and potential supply exceeds demand). In my dealership, my Dad got one made 3 weeks before the summer shutdown at Wolfsburg, mine had an allocated build week just after, and mcmaddy was about 3 weeks after that. You might find that a dealership has not sold all of their allocation slots, so they get an order placed and it goes on the next allocation slot available to the dealer which may be as little as a month away.
My dad's GTD got built in BW25 and I think it was the first UK GTD on this website after order placed in BW13 - 12 weeks wait. Conversely, mine was ordered BW12, confirmed for BW33 but actually built in BW 35 - 23 weeks wait, and I ordered before him at the same dealership but an administrative error on mine following a change of colour saw his jumping the queue.