What do you mean by "established"? Are you talking about establishing the nitrogen cycle in the water and/or the soil? I wouldn't worry about it too much with FBTs, I think they can handle the ammonia spike no problem. If you are concerned, you can buy Stability or a similar product and add it to the water to speed up the process. But unless you have a source of nitrogen (e.g., frog poop) in the water already, the bacteria will not become established. With Stability, the ammonia spike will done with in a few days.
The only other thing that may be a concern may be pesticides on the plants, if you bought them from a mass supplier. This may only be a problem if crickets chew on the leaves and the frogs eat the crickets. I usually give plants a quick spray-down before putting them in.