I made the Inca trail in 3 days with a bunch of friends, but that was before they started to limit access to it(it was back in the day when i was younger

).
Now you NEED a tour operator to book you in

and going on your own isn't a good idea(you will need to wait if you don't plan ahead coz a max of 500 people are allowed each day in the trail).
There is also another 7 days longer route for the Inca trail which has far less tourists, if you have the time get it.