Just been running this for 30mins at around 3 KH/s, but my Pending Balance is still zero.

How soon should I expect the pending balance to increase?
Thanks

1)  Pending balance first shows up after 60 blocks of mining

2) If you spent like 10kh/s on a stuck pool for hours you will probably get nothing because the pool won't find the block.
   If it does you'll only get your share of this one block you spent hours mining on.