You say "There is no evidence that shows how much time was involved" but you also claim the hard parts developed simultaneously. If you are a scientist, please explain the apparent contradiction to this non-scientist.
The fossil record all over the world simultaneously (to the best of our ABILITY to measure) suddenly develops hard parts. If you bothered to read for comprehension I state that it is most likely that it took millions of years to occur, there is simply no time references available.