I don't think there is a "speed of entanglement". Particles are created in an entangled state and remain so until the state decays, wherever they happen to be.
It's like painting two things the same colour. Would you talk about "the speed of green" as they separate?
Typical usage of the phrase "speed of entanglement" refers to how fast the correlation is established following a measurement of one of the components. Currently the lower bound is on order 104 c, IIRC.
Of course, most believe that the actual answer is "infinitely fast".