A computer-implemented method of triggering an instance of companion software to perform an expected action related to a piece of media content during a delivery of that media content by a media device to a content consuming user, the method comprising, by the instance of the companion software: receiving (S302, S316) a synchronization signal transmitted when, in delivering the media content, the media device reaches a reference point in the media content, wherein the synchronisation signal conveys a time instant of that reference point; accessing computer storage holding an association of the expected action with a time instant of a trigger point in the media content; measuring a current elapsed time from the time instant of the reference point; determining a local confidence value based on the current elapsed time, the local confidence value indicative of the likelihood of the expected action being triggered at a correct time, the correct time being when the media device, in delivering the media content, reaches the trigger point, wherein the local confidence value decays from a first value set on receipt of the synchronisation signal over the duration of a wait interval; measuring a signal confidence value representing an ability to be able to detect an underlying carrier signal used to convey the received synchronization signal, augmenting the local confidence value with the signal confidence value, wherein the rate of decay of the local confidence value is reduced if the signal confidence value is at higher level and the rate of decay of the local confidence value is increased if the signal confidence value is at a lower level; and triggering the expected action when the current elapsed time matches the time instant of the trigger point conditional on the local confidence value as augmented being within a first confidence value limit. receiving (S302, S316) a synchronization signal transmitted when, in delivering the media content, the media device reaches a reference point in the media content, wherein the synchronisation signal conveys a time instant of that reference point; accessing computer storage holding an association of the expected action with a time instant of a trigger point in the media content; measuring a current elapsed time from the time instant of the reference point; determining a local confidence value based on the current elapsed time, the local confidence value indicative of the likelihood of the expected action being triggered at a correct time, the correct time being when the media device, in delivering the media content, reaches the trigger point, wherein the local confidence value decays from a first value set on receipt of the synchronisation signal over the duration of a wait interval; measuring a signal confidence value representing an ability to be able to detect an underlying carrier signal used to convey the received synchronization signal, augmenting the local confidence value with the signal confidence value, wherein the rate of decay of the local confidence value is reduced if the signal confidence value is at higher level and the rate of decay of the local confidence value is increased if the signal confidence value is at a lower level; and triggering the expected action when the current elapsed time matches the time instant of the trigger point conditional on the local confidence value as augmented being within a first confidence value limit.