Clark knew that Tim was coming by and wanted to be there to greet him when he finally did arrive. He sometimes helped those who first showed up, knowing that they would need someone to fill them in on all the specifics when they got to the apartments, but this time he really wanted to be around to help out for a more specific reason that wasn't just being helpful in itself. Tim knew him from the future. Or of him, at least. That meant that they were probably from the same universe, which also meant that the boy was going to need a more familiar face to greet him than any of the stranger few around here. It was always better to handle this sort of situation with a friendly face than an alien (ha) one, in his opinion.
Clark had been hanging around the front area when he saw someone enter the building. The face certainly wasn't one that he himself recognized, which meant that there was a very good chance that this was the guy he'd been waiting for. Or maybe someone had ordered pizza. Who knew?
"Tim?" He started, moving toward the boy with a polite sort of smile. "Is that you?"