According to "Thiaoouba Prophecy", each of us will need 120,000 years to go to a ninth category in the worst case. I wonder if it could take more than 120,000 years, but anyway, if they say this, this must be some kind of good statistics -- and as in most statistics, probably there are outliers.
"If, through the numerous experiences you have in your life, you ensure your Astral body benefits in a spiritual sense, it will acquire more and more spiritual understanding. In time, which can vary from 500 to even 15 000 of your Earth years, your Higher-self will have nothing more to filter."
I believe also that all HSs have been initially placed on the first category, too. The book states explicitly that they too evolve. I believe that probably, they would need the same time to go upwards -- each of them is a bigger spiritual organism than we are, but he/she also lives more lives at the same time than we do, so the difference cancels out.
Now, in the cosmic scale of things, 120,000 are very little time. Most stars live many billions of years, so when a universe like ours is created, after the first stars form and then the first planets form, the time frame between the inhabited first planets of the first category, and the inhabiting of the higher categories, including the highest nine, is quite negligible. Plus, it would give God some time to fix errors in his design
through the HSs.
My actual wonder is in the following. We are living roughly 12-14 billion years after the creation of the universe. If I was created at the beginning of the universe, I very much think that by this time, I would have either reached category nine and beyond, or I would have been totally recycled by Nature because of too much errors.
That is why I have started thinking that souls are created in batches over the life time of the universe, according to supply and demand in the universe, i.e. when a soul leaves category nine to join the Creator, demand rises
.