I'm just wondering. The 2nd Division landed in Europe in June 1944. They continued to fight through 1944 and after the Bulge in December 1944, they moved toward Germany. Since your father didn't join the 23rd until January 1945, I would guess he was a replacement for men lost at the Bulge. Whether he went right into the 23rd or was pulled from a Replacement Depot I don't know.
i'm not sure when he joined the 23rd, out of basic or like you said a replacement depot, he doesn't seem to remember, I know he arrived in Europe jan. 30th, he does have medals for fighting in central Europe and the Rhineland, he does remember crossing the rhine river and from help with some of the members here I figure he was wounded around the weser river heights area april. 5th
He wouldn't have joined the 23d directly out of BT, since they were already over in Europe. He would have gone into the Replacement system and then was assigned to the 23d to replace their battle losses. I had 2 uncles who were assigned to their units through the Replacement system - one in the ETO and one in the PTO.