It takes around 18 minutes to whisk egg white.
When whisking egg whites it's much easier and faster to use an electric handheld mixer or other electric mixer to whisk the egg whites.
You can also whisk the egg white by hand but it takes longer and is more tedious and you might get sore hands or arms.
I recommend using an electric food mixer which speeds up the process and makes it easier.
Either way it should take between 12 to 18 minutes to whisk the egg white.
As you continue to whip more air into your egg whites, you should reach maximum volume for the egg whites in 12 to 18 minutes.
Whisking the egg whites by hand to a stiff peak stage requires tremendous arm strength and much more time.
It will take several minutes to achieve stiff peaks when whisking by hand.