How long to get an accepted share? I am very new to bitcoin mining and am unsure if I set up GUIMiner correctly. I have a new MacBook Pro with a discrete graphics card (ATI Radeon R9 M370X) and am getting about 129 Mhash/s according to GUIMiner. However, it says "Shares: 0 accepted" in the bottom left side of the window. How long does it take for shares to accumulate? Did I set something up wrong? It has been running for about 3.5 hours.

Thanks!
The Bitcoin network has a global block difficulty. Valid blocks must
  have a hash below this target. Mining pools also have a pool-specific
  share difficulty setting a lower limit for shares.


ASIC hardware is required for profitable mining because the current difficulty is extremely high as a result of increased hashing power coming online. GPU mining is unable to compete with this specialized hardware. It is most likely the case that your GPU is unable to find any valid shares within the ~10 minute timeframe that occurs between discovery of new blocks.

See this response for more information