Withdrawals are automatic when a person's account has earned 0.1BTC, or, if the account is nearly complete and it crosses the 0.1BTC threshold, it will delay that withdrawal until the account is complete.

Warning: Wildly inaccurate numbers ahead!  Use the concept, not the numbers.

Let's say that you deposited 1BTC, and your reward is 110%.  Complete Reward time is currently listed at 56 months...  which will go down when new hardware comes online and will go up when the network difficulty changes.

But, let's assume the reward time remains constant.

This means that in 5.1 months, you'll get a payment of 0.1BTC, and will continue to get the same payment 11 times total.  If the final payment were for 0.1001BTC, then you'll have to wait the extra day for that extra 0.0001 to come in.

If you deposited 10BTC, you'll be getting a payment roughly every 14 days...  100BTC == roughly every day and a half.