River could have easily waited in the console room for the Doctor to come bounding in, but she figured he would want a moment with his TARDIS. There was also the fact there were others on board that would also need to say hello, so she would let him come find her for once. Really, constantly chasing him down was tiring, might as well let him do the chasing for once.
Though River was conflicted over the Doctor's arrival. He knew who she was and what ultimately happened to her parents, so that was good. What wasn't good was that he had no memory of being here before. Which left her with having to explain about the Master and Romana. She knew all too well he would not like the tale she had to tell, especially about how Romana was dead. Two more Time Lords were dead, one killed by both Eleven and Nine, the other dead by accident and refusing to regenerate. Instead, River now held the rest of Romana's regnerations. She did wonder just how much of Romana's being passed into her, if any, because River was starting to see some touches of what she could only describe as the War Queen.
Now, River never was the pacifist by any stretch of the imagination, but she felt as though she had more of the driven warrior thing about her in this regeneration. While she'd always enjoyed guns, she seemed to have far too much of a love of the collection her Christmas wish had brought her. So while waiting for the Doctor to make his appearance, River was in her room, cleaning one of the handguns she'd gotten. It was soothing to take it apart and clean it and put it back together. It was something that at least helped dampen the fire she felt within her soul. Perhaps this was something that stuck with Time Lords, that regenerating in the heat of battle left a very deep impression upon the new regeneration.
When the knocks and question came, River looked up from the chair she sat in to see the Doctor's head poking into the room. Putting the last piece of the revolver back into place, she smiled and stood up. "Come in, sweetie." At least her use of the word sweetie seemed to carry over from the previous regeneration. Walking over to a chest, she opened it, revealing part of her arsenal from her wish briefly as she put the revolver back in its place, then closed and locked it before turning back to the Doctor. "Make yourself comfortable." Though she was rather expecting the Doctor to come right over to her and inspect her in this new regeneration. After all, she was different from the River he'd last seen. There was also the fact she'd gained some height in this regeneration and was now almost as tall as Eleven was.