Is going from 10 mg prozac (fluoxetine) to 40 mg ok, and how long to see results?

It depends: Results (and their speed) depend on the reasons you're being prescribed the Prozac (fluoxetine) to begin with. Going from 10 mg to 40 mg is a big jump, and as a physician i would be more gradual about it. Generally one needs several weeks to notice changes. Since you've shared no info about why you were prescribed prozac, (fluoxetine) i can't really comment further.