You are correct, one aspect. And the first week?
To feel confident in fighting Hood, Thomas would need all three of Smith's divisions available. Two of them were just getting off the riverboats on Nov. 30; the other would be disembarking on Dec. 1. At the same time, Steedman's troops were ordered to Nashville on Nov. 30 and arrived near Nashville late on Dec. 1.
What this means is that by late on December 1, Thomas has 15,000 reinforcements at Nashville (at least 2/3rds of them tough veterans). Barring the destruction of Schofield's troops, Hood is already too late to take Nashville unless he gets there in time to attack on Nov. 30. Late on Nov. 30, Hood is just approaching Franklin. The race for Nashville was already won by the Union as December 1 dawned.
Early on November 30, Thomas was hoping he could get Smith moving out to Brentwood late that day; the realities of movement made that impossible. About 11:30 PM he was hoping to have Smith and Steedman moving out to Brentwood on December 1; that was also too optimistic. When you consider the practical matters involved in getting Smith off the transports and organized, and of Steedman taking the trains from Cowan while wondering if he was about to be ambushed, then getting his troops shaken out for movement, any forward movement by Thomas is limited. He might have gotten 2 of Smith's divisions moving on December 2, but only for a short distance. He probably cannot have all of Smith plus Steedman operational in the field (say more than 8-10 miles from Nashville) before December 3. (The horses and wagons of the supply train also have to be disembarked, unloaded from the trains, etc. then organized and routed to the right spots, etc.)
Thomas was hoping to do that quicker. Maybe he could have done it. He was a general and a good one; many of the troops involved were veterans. I'm just a guy who likes to read military history. But for ordinary generals in ordinary times, getting those reinforcements out in the field on December 3 would be pretty good.
Add to this the condition of Schofield's arriving troops. They'd just been hustled back from the Georgia line, almost surrounded, escaping via more than one night march, and through a vicious battle. They are arriving in Nashville on December 1, tired and worn down.
Wilson's troopers are also worn out. Their horses are broken down, they need some reorganization, theit commander is just arrived, has been roughly handled by Forrest, and needs to get a grip on his command.
A truly aggressive, charismatic, driving commander might have gotten all that combined, turned around, and out in Hood's face on December 2 or 3. Maybe Sheridan, Lee, Jackson, Forrest or Grant would have done it. Maybe one or two others. Lots of good commanders would not have done it.
That means it is reasonable to expect Thomas to do it sometime later. In fact, the Battle of Nashville is fought Dec. 15-16. That's not a lot of time, given the need to get all this shaken into order and refitted a bit, plus the weather.
No one was going to move in the ice storm in any case, so it is really a matter of moving very quickly -- or exactly when Thomas did move. If Grant had actually been in Nashville, he probably wouldn't have moved too much faster. Based on his personality, he might have started out to hit Hood before the 10th. But if Grant had decided that he needed to take time to put his Army in order, he'd have done that as well. The big difference is that Grant would have managed the relationship back to HQ and Washington much better than Thomas did.
Tim