You actually have no idea when and if the other entangled thing was measured. I'm at my limits of understanding, but I believe it makes no difference when you collapse them. You could do it before moving them apart and the whole process is the same. In fact, process is probably an inadequate word. The particles always shared a state. There aren't two particles; there's a system, and that system was created from 2 particles. You don't observe a particle, you observe the system. You know everything about the system from the single observation