reserve approximately 50% (49.4%) of your profit. 35% federal, 9.3% california, 1% california mental health service act, 15.3% federal self-employment tax (12.4 for ss + 2.9 for medicare). luckily federal self-employment tax is caped and deductible but in general reserve 50% after profit also you might want to consider california tax exempt munis. while the yields are lower (ie: 4%) vs 5% or whatever you are getting from hsbc, hsbc is taxed at your income which will be 50%, which makes tax exempt munis attractive @ your bracket.
btw 540es & 1040es are due september 15th so hopefully you talk to your accountant before then in case you havent been submitting quarterly estimate payments