Since you are just talking about the atmosphere and perhaps tectonic shifts, you can say that it is still forming now. Most people would not, most people, even most scientists would consider the "formation" of the planet to be a far more dramatic event. But what most people do, how they use words, what has been accepted, has not influenced you to this point. Why should it now? By all means continue with your own faith based belief system with its own interpretation of words. That is what most people do.