How common is it for planned extraterrestrial manipulations to be delayed? Was this true for 9/11 as well? Was it originally planned to happen on an earlier date?

It is not uncommon for plans to shift and change in their timing because the workings of the Extraterrestrial Alliance are complex, multi-component in nature, and multi-sourced, given there are three main civilizations who are members of the alliance and things many times are difficult to synchronize due to somewhat competing priorities, interests, and political forces among the membership. In addition, are the complexities of many of the schemes that rely on successful manipulation of human agents to carry out key steps in the orchestration. This at times is much like herding kittens, somewhat uncertain in effectiveness, and might require several attempts for everything to line up with a series of preliminary actions needed. The 9/11 attack on the United States was no different. Even though it was for a large-scale enterprise to launch a wider war, it was, in fact, scheduled to happen sooner than took place. So even though it looks in hindsight to have been intentional for that date to coincide with the widespread understanding in the U.S. of 911 as the number for reaching the first responders when there is an emergency, especially lawbreaking, that was not the original planning but happened as a lucky consequence of needing time to get everything lined up.