Seconds. They unlock the door, come in yelling, they guy is covered with a blanket and he wakes up (probably very confused and scared), and as he sits up, they shoot him several times.
Probably before he even realized what was happening.
Your statements don't contain the actual details.
They did not come in yelling random stuff. They came in yelling over and over,
"police, search warrant."
The steps for a no knock search warrant are to (1) announce who is entering, which the police did; (2) announce why they are entering, which they correctly did that, too; they were yelling "search warrant."
The argument for the no knock search warrant is so that evidence does not get destroyed. The MPD, of course, was assisting the St Paul PD in the investigation of the murder of a St Paul Black man. The family of the murdered Black man wants justice, too.
Amir sat up, yes, but
you left out that he pointed a loaded gun at one of the officers. Like it or not, but the officer responded in the way he was trained.
The officers on scene didn't do anything wrong; they followed procedures from the moment they unlocked the door. The issue, of course, is with the no knock. Are they really needed? Could you wait until the suspect entered the building and show him the search warrant then, for example. This is why there is now an immediate moratorium on no knocks in the City of Minneapolis. The issue is, once again, getting revisited.