When you're deep frying french fries it takes between 3 to 8 minutes.
Get the deep fryer cooking oil up to temperature and then add the french fries to the hot cooking oil.
Watch the french fries closely so that they don't overcook.
In my experience deep frying french fries takes 5 minutes at most but you might like your done more but just don't burn them.
It's possible to overcook the french fries and forget about them so stand near the deep fryer at all times while cooking the deep fried french fries.
Frozen french fries usually take a bit longer to cook but the thawed french fries are usually fully cooked in 5 to 8 minutes and sometime as soon as 3 to 4 minutes.