Months.
Leica is a small company. Very small.
And still does a lot of hand-assembly. They pride themselves on this; and buyers are willing to pay for it.
Thus, their prices are high, and their production capacity is low.
And I wouldn't be surprised that they run up into surprises with the complexity of some of their assemblies, leading to high failure rate, rejection and rework, all which lead to even longer backlog (e.g. 35-70 f2.8 zoom was one I recall, now a very expensive lens, the f1.2 Noctilux was notoriously difficult to make)
I also hear that Asian distributors are getting a higher proportion of units, as their sales are higher and more profitable there. You might be able to move up the waiting list if you deal through Asia.
Vick