So how long should i give it until i know its going to stay healthy?
That's difficult to say as it depends on several factors. For instance, what kind of environment are you able to provide? I have most of my tender things in a fairly cold basement where very little growth is occurring now. These plants are sort of 'semi-dormant', not truly dormant but greatly slowed so I won't re-pot any of those now. On the other hand, I have a smaller setup that is in a warmer bedroom and I recently re-potted a small Ficus that I rooted. It is doing well but it is in a better situation than the ones in the basement, a little better lighting, warmer temperatures and a generously sized humidity tray. What are your conditions like?
Something else to consider is that it is very likely that your plant has been re-potted fairly recently so another insult so soon may not be prudent. Provide the best conditions you can, observe it for a month or so and go from there. Just so you know Ficus respond well to being re-potted in summer, when they are actively growing they recover quickly.
One more thing, I keep Ficus (all my tender species really) outside during summer, they really do better there. They can be kept inside year-round but my lighting is so poor in the basement that it is not really an option for me.