Not sure what you are talking about here, he was with the 7th Calvary, as he had been for nearly ten years. The officers and men were very familiar with Custer and his tactics.
He had 718 men under direct command.
Of that 718, roughly a third of his officers and 200 men were detached and unavailable to him.
Of the remaining 500, 250 were raw recruits.
Of the remaining 250, about half had served with him over the last 5 years, and the remainder were Civil war vets who had signed on from before that.
So that leaves him with a core of about 125 men who had served with him beyond one engagement with the indians during the indian war.
That’s not very many men.