if i point my rig to a pool even when the coin hasnt launched, it will start to mine when coin starts ?
I believe so. Don't take my word for it though.
Worked perfectly for me with ZEITcoin. I slept through the coinstart, and later checked the logfiles. Miner switched to the pool at 6:16, which was probably 16 minutes after coinstart.
But of course, it all depends on how clever the pool owner is. How long does he need until he has installed everything.