The USCCB Committee on Divine Worship informed me that this was incorrect. The anticipated Sunday Vigil Mass on late afternoon/evening Saturday only fulfills the obligation for Sunday, not for the Solemnity of the Immaculate Conception. I called them twice about this matter in order to get the correct information.
In order to satisfy the obligation for the Solemnity of the Immaculate Conception, you need to go either to the anticipated vigil Mass on Friday evening or on Saturday morning/early afternoon. I’ve been taking through the ringers for my stance by several people, but, inasmuch as I don’t agree with some of what the USCCB has done, they do have the authority and it falls under their competence to determine this matter.
If you cannot go to Mass at all on the Solemnity of the Immaculate Conception, it is best to contact your parish priest.