We present fiber bundle models of creep rupture of fiber composites considering two different microscopic mechanisms that can lead to time dependent macroscopic behavior: (i) the fibers themselves are visco-elastic showing time dependent deformation under a constant load and break when their deformation exceeds a stochastically distributed threshold value. (ii) The fibers are linearly elastic until they break in a stochastic manner, however, the load on them does not drop down to zero instantaneously after breaking, due to the creeping matrix, they undergo a slow relaxation process. Assuming global load sharing following fiber failure, we show by analytic calculations and computer simulations in both models that increasing the external load a transition takes place in the system from a partially failed state of infinite lifetime to a state where global failure occurs at a finite time. It was found that irrespective of the details of the two models, a universal behavior emerges in the vicinity of the critical point: the relaxation time and the lifetime of the composite exhibit a power law divergence with an exponent independent of the disorder distribution of fiber strength. Above the critical point the lifetime of the bundle has a universal scaling with the system size. On the micro level the process of fiber breaking is characterized by a power law distribution of waiting times between consecutive fiber breaks below and above the critical load.