Does anyone know what Ryanair’s “free move” policy is for flight retimings of less than 3 hours?

On the schedule change email they offer a weblink to accept the new timings, or suggest calling to discuss moving the flight for free.

It would be great to know what the acceptable parameters are around moving the flight. Is it 3 days, a week, a month, or to the end of the booking window? (The latter would be ideal given the destination is not on the Irish travel green list).