Finishing writing a book, Ph.D. or a new curriculum is subject to Hofstadter’s law which states”It always takes longer than expected, even when you take into account Hofstadter’s law.”
Try individually polling the group you are working with and ask someone who has done it before.
But as a general rule of thumb.
If you have been waiting for the project to finish for the last two months, don’t expect it tomorrow, expect it in a couple of month’s time.