Is the last stage of balding always so fast?

During years me and my friends were balding and this year my friends went from diffuse thining to NW4/5 with a hairline.  Even me before iv’e started Fin my hairloss went full speed in less then a year. From a NW1.5 to NW3 with crown thinning…

Does it always happen?

It all depends upon your genetics. Young men who inherit an advanced balding pattern usually get it by the time that they are 26 years old and will see the hair fall away rapidly starting somewhere between 17-21, Look at your parents family patterns (mother and father) so see what you might expect to see in yourself. Find a good doctor and build a proper Master Plan with that doctor to manage the hair loss if you are in this situation.