Originally as per Zhou Tian's plan, he was prepared to invade a Mainland. With Zhou Tian's strength, although he believed his faction would not be considered powerful on that Mainland, as long as his current territory was not lost, Zhou Tian had the confidence to compete with those forces.
In the worst case scenario, he had no means to expand his territory, but possessing enough foundations, Zhou Tian didn't need to worry about those forces. Therefore, in that situation, Zhou Tian had no hesitation in his plans.
It was only because he had been unable to disengage before that Zhou Tian had not taken action after preparing his plan. Now, however, his own camp was stable and that organization was unlikely to invade the Main Plane. Now, free from any hang-ups, knowing the position of the mainland, Zhou Tian was bound to take action.