@turquoise-- I think cream for genital warts works better for some people than others. But it can take months, so I agree that the treatment should be continued until your doctor tells you to stop.
The strength of the cream is important as well. For example, imiquimod cream comes in 1% and 5% strength. 5% is more effective against genital warts.
Unfortunately, as with most wart medication, there is a chance that the warts will come back after using the cream. But usually, it doesn't.