Just because the negotiations play out in public, it doesn't mean the actual details, signing of contract, medical etc. get done any quicker.
You don't announce anything until confirmation is received from the FA, which is always slower during the window.
And these days, you have to add in the production and editing of photos/video montages/posing in merchandise etc.
All sorted before the deadline to play at the weekend is the only thing that anyone needed to worry about.
When it gets announced is pretty irrelevant.