A fsm with temporal events I have defined a finite state machine 


    Q = {Σ, S, s0, δ, F}

    where 

    Σ = {'[r]equest', '[o]ut', '[i]n', '[e]nd'}

    S = {'[R]eady', '[I]nitiating', '[W]aiting', 'Re[C]eived', 'Re[S]etting'}

    s0 = R,

    F = {R}

    δ =  (q ∈ S and x ∈ Σ)

     q      x      q
    -------------------
     R      r      I
     I      o      W
     W      i      C
     C      e      S
     S      ∈      R


However, I have a transition from  W to S via a temporal event†. How should I represent it?
If I add an epsilon-move
     W    ∈      S
it is not intuitive that it is a temporal event. 

†possibly a timeout
This was a comment first, but Suresh asked me to turn it into an answer:

Maybe you want to take a look at timed automata. These are finite automata equipped with clocks; time can pass, clocks can be reset, transitions can be restricted to occur within a given time by clock guards etc. Here are some nice introductory slides: lsv.ens-cachan.fr/~bouyer/files/bouyer_chennai.pdf

(This is actually the framework that Vor is using in his answer. His solution makes use of a clock that is reset and a guard for the epsilon transition.)