Here's some helpful advice on making an Inca Trail Reservation. It is recommended that you make a reservation for the Inca Trail and pay for your entrance fee well in advance.
Reservation bookings should be done:
December, January, March: 3-5 weeks in advance
April, October, November: 6-8 weeks in advance
May, September: 2-3 months in advance
June, July, August: 3-4 months in advance
In Feburary the the Inca Trail is closed. You can still visit
Machu Picchu.