You'll first notice it in gameplay. Something as small as a body part obstructing the direct line of sight to the console can interfere with the left joycon connection.
Go straight into your calibration tools and do the control stick test. First rotate both left and right joycons while holding it in front of you. Notice it should be completely responsive without any input lag/stutter.
Now put both behind your back and repeat the steps. You'll notice that the right joycon is still as responsive but the left joycon has very noticeable stutter. If that is the case, call Nintendo and get them expedited for repair/replacement immediately.
I'm still waiting on mine, it shipped on Monday and could take anywhere from as little as 4 days to as long as 3 weeks (what a range huh?)
Go straight into your calibration tools and do the control stick test. First rotate both left and right joycons while holding it in front of you. Notice it should be completely responsive without any input lag/stutter.
Now put both behind your back and repeat the steps. You'll notice that the right joycon is still as responsive but the left joycon has very noticeable stutter. If that is the case, call Nintendo and get them expedited for repair/replacement immediately.
I'm still waiting on mine, it shipped on Monday and could take anywhere from as little as 4 days to as long as 3 weeks (what a range huh?)