Obviously pre-paying is a risk as it's non-refundable.
There must be a point though, close to whatever date you want, that the prepay option disappears.
Is this cutoff determined by Marriott? The actual property?

As a rule, does anyone know the typical period of time before a specific date that this option disappears?
Just trying to save some money while minimizing the risk of cancelation and losing the money.

thx