We are currently working on how the community fund works and estimate that it will become active earliest in Q3 of 2022.
As already promised, if you have accidentally activated the flag, there will be a time period where you can revert this choice. Note however that currently having set the flag does not have any effect on your neuron: you can vote and get rewards as with any other neuron.
So to address your specific question: I am not sure yet when exactly the decision can be reverted, but this will be defined in time. As the actual change is still a bit away there is still enough time to allow users to make this change.
I am also happy to share that @bjoernek will lead this feature going forward!
So he will probably be the person sharing future updates and the best person to answer further questions!