With experience and optimal prerequisites (good connections to a notary, single founder with default bylaws and no asset transfer into the company) you can do it in ~4 days, e.g. for a holding company.

I did it in ~2 weeks last year, where almost a week was caused by the coworking space I rent at not notifying me of the physical mail from the court. If that physical mail would be eliminated from the process you could probably do it in 2 days.

Apart from that, for any non-trivial situation, the majority of the time will be determined by how fast you can proceed through the process of adjusting your bylaws, etc. and evaluating tax situation (so lawyer + tax advisor waiting time).

(after that the process of waiting for a tax ID starts, which depending on where you live can easily be the slowest part and take ~6 weeks on its own.)