How about ALL Odumbo's executive orders, not just that one.
He can't just issue an executive order rescinding all previous executive orders. He has to rescind them by specific executive order, such as : Executive Order # of January 22, 2006, concerning such and such, is revoked.. Now, he can list all the executive orders he is rescinding in one executive order. So, I think the very first one listed will have to do immigration. Therefore, technically, that would be the first one revoked.