Wait for the click.

Do not rush the start of your deadlift just to escape the discomfort of a proper setup. Keep pulling tension through the bar until the top of its sleeves ‘click’ into contact with the top of the openings in the plates.
Do not rush
It's going to be very important to be patient in the start. A lot of athletes tend to want to rush the start and jerk the bar off the floor, and when they do that sometimes they relax their arms and then pull and put their biceps in a compromised position.
Juggernaut
I'm literally trying to think about wedging my body between the floor and the barbell, pulling that slack out [before] I explode.
Neversate
We see a lot of people rush the bar off the ground... and they'll lock their knees too early. Be patient. If it takes a minute to come off... the ground that's okay. Stay in position. You'll finish.
Super Training
It doesn't matter how fast you can get the weight off the floor if you can't lock it out. So instead I like to think about being patient... because otherwise I lose that position... [By] keeping my lats set, I can get that explosion towards the top of the lift rather than the bottom - where all that momentum is kind of wasted.
Juggernaut
Not being tight and trying to rip the  bar off the floor is a recipe for injury. What I see happen every time is the lifter getting in position without getting tight. When they start the pull, they get pitched over the bar, round their back, and make the lockout much harder than it has to be.
Keep pulling until 'click'
PULL THE SLACK OUT
PULL THE SLACK OUT
PULL THE SLACK OUT
PULL THE SLACK OUT
whiteboard_daily
A good wedge will cause you to feel like you’re trying to hold up a wall so it doesn’t fall on you, but will also cause the bar to pull up into the plates, and likely cause the weights to lift slightly off the floor if the weight is light enough.
Dean Somerset
If you listen to a bar when you go up to it, even if there's 135 on it, and you just slightly lift the bar, you're gonna hear a click. That's the bar clicking against the shaft, where the sleeve is.... You go up to the bar, you grab the bar, you [get tight] until you hear a click. Then when you hear the click, PULL... Tighten everything, and then pull.
Elite FTS
You'll see the bar almost comes off the ground before I even pull it because I'm so tight. You want to get really tight through your lats, upper back, hamstrings and the bar will almost be pulling off the ground before you even try to pull... Rather than pull for speed, I try to ease the bar off the floor... otherwise you're going to get to your knees, it's going to whip hard and you'll miss your lockouts.
Animal
If a lifter doesn't pull the bar up so that it's making contact with the top of the rim in the hole of the plates, he's initially not going to be working against any resistance. By not working against any resistance, it's extremely difficult to produce an isometric contraction in the spinal erector musculature and the lats that's strong enough to lock the lumbar spine into extension during the movement.
You need to make sure your body is tight enough that your form won’t disintegrate as soon as you start lifting the bar. This is often called “pulling the slack out of the bar.” I prefer to think of it as “pulling tension into your body,” because there’s not really any “slack” in the bar.
Stronger By Science
Create as much tension throughout your body as humanly possible before adding the extra force required to start pulling the rep.
Stronger By Science
We're going to be relatively well-balanced by the time we find this tension... It's going to feel like the bar almost wants to float off the floor (especially with lighter weights)... This position is going to be highly individual... within a range of good positions. So play around a little bit but pay attention to the outcome of the changes that you make.
Calgary Barbell