Work is due to start at Worthy Farm in March 2021 ahead of the festival taking place next June.
Speaking on the Behind The Noise Podcast, Entertainment lawyer Ben Challis said: "For 2021 we will have to start building in March, or the end of March because its a big festival and it takes a lot to build, and no one wants to do a 'light Glastonbury'.
He added: "The plan would be to rebook the 2020 bill, it will move everything, including our 50th-anniversary celebration to 2021."
When asked if people had sought a refund when the 2020 event was cancelled Challis said: "It was literally a handful, it was extraordinary. No one wanted a refund."