I didn't even apply until I had my Decree through, not worth the risk. Best to always make sure everything is as clear as day before proceeding.
It is easy to cancel a divorce, or problems can arise that take longer than 6 months to sort out, the embassy will not take that risk.
By the way, I done my own divorce, took 10 days from applying to getting the decree. Cost about £60 back in 1999