So why not do it simple and do something like...
NPC Code:
if (playerenters) timeout=20;
if (timeout) setlevel2 blahblah.nw,x,y;
EDIT: don't forget, you might want to warp them to the gmap instead(if that's where you're warping them) and thus, you need to find the gmap coordinates. Also, setlevel2 is serverside, not clientside.