While looking through releases today, I stumbled across an OLD thread release I made to play sounds to joining players...and only joining players, using sounds included with HalfLife I think.
(ie, think i avoided custom stuff)
It didn't use connect, it used playerauthed hook (basically, it made sure they stayed long enough to steam authenticate)
Look for UJoin sounder for old example code.
And, I mean OLD...pre GM12 I think...but, with little lua experience, would make good starting code to modify for your needs.