The time it takes for sun to damage eyes is 100 seconds or less of looking directly into the sun.
According to medical professionals blindness and permanent retinal damage can occur when someone looks at the sun for 100 seconds or less.
This is under two minutes but ultimately, how long it takes for eye damage and permanent blindness to occur depends on several factors, such as the dilation of the pupil and the sun's intensity on that specific day.
To go blind from staring at or looking directly at the sun you would have to stare at the sun more than a minute or two.
The suns rays are so powerful that your eyes will prevent you from staring at the sun for more than a split second.
If you try staring at the bright sun without any sunglasses then your eyelids will close and your head will likely drop or move away from the sun to prevent eye damage.
You can use a welders helmet if you want to look directly at the sun without damaging your eyes.