No, because that would cause %t to be evaluated only when the timer triggers, and here %t is a local variable that will be long gone by then.
As suggested by westor (and indeed, several others before) the feature would end the nightmare of double evaluation with timer commands, for which there just is no simple, reliable workaround. As such, this feature is long overdue, and should be compared to e.g. the 'n' flag to $read.