State machines with temporary events

Question

I determined the final 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 through a temporary event, i.e. The transition should occur after a certain amount of time. How can I handle this?