The voting for charity should be done before the funds are collected for that month. I'd hate for you to turn people off by using their coins for a cause they do not want to support. Think about it. Losing the vote for which charity receives the funds before funds have been secured would only make you be more active in the community to win the next months charity of choice instead of feeling robbed and quitting the community.
Thinking it through I think the time frame should be a week at a time to increase community involvement.
Oh yah this is absolutely what we will be doing. It may not have been explained so properly but all community voting will in fact happen before the initial fundraising begins. We want to make sure people know what they're contributing to and how the funds will help. In fact we have a few community outreach managers to make true direct contact with each organization, outside of the internet, to form a lasting and mutually beneficial relationship.