There is a planner at http://www.i-orp.com
that you might wish to consult. I believe it will help you to decide from which accounts to withdraw (taxable or tax deferred). I've not checked it out myself because I have access to a similar planner through my brokerage account.
Edit: I tried out the planner I mentioned above - it does not have the flexibility to provide different returns based on alternative withdrawal strategies. The software available to Schwab clients allows one to set up a sequence of withdrawals (taxable then tax deferred then Roth) and gives you an estimated balance at the end of X number of years. You can then change the sequence, for example tax deferred before taxable, and it will then provide a new estimated balance.
I think this type of sequencing is more important than when you take withdrawals during the year.