Fatal problems:
1. The resurrection was in the morning:
KJV Hosea 6:1 Come, and let us return unto the LORD: for he hath torn, and he will heal us; he hath smitten, and he will bind us up. 2 After two days will he revive us: in the third day he will raise us up, and we shall live in his sight. 3 Then shall we know, if we follow on to know the LORD: his going forth is prepared as the morning; and he shall come unto us as the rain, as the latter and former rain unto the earth.
2. Luke 24:21 would necessarily take place on Sunday:
KJV Luke 24:21 But we trusted that it had been he which should have redeemed Israel: and beside all this, to day is the third day since these things were done.
But clearly, Sunday can do no better than be the 4th day since these things were done.
Ref: (http://www.lamblion.com/articles/articles_issues14.php).
Now you will see that this has neither problem:
1. For Luke 24:21 count days since the crucifixion making sabbath day after the resurrection the 3rd day "since" (counting exclusively just like in Dr. Regan's scenario.