No it is not working on the 10th toss and that is the great lie of evolution - that it just takes a little mutation to achieve great things. I have already explained how because of genetics even after such a great change is accomplished it would be very hard to spread it through a large population. In order for evolution to have been responsible for the descent of man from an amoeba thousands of new genes, thousands of new proteins, thousands of new characteristics had to have arisen. These things could only have arisen by the creation of new genes and to make a gene that works takes a large amount of random tries and each one up to the last is the first try. The reason is simple - selection does not know what it is looking for, selection cannot act on a gene that is not working yet. Selection can only act when the gene is complete and in working order. So you cannot create a gene through selection, it can created by random chance and that is an almost total impossibility.
Sure it does: Survival
For example, consider "Creationism" as a gene defect. Creationism evolved as the answer to Bronze Age man's quest for understanding the universe. As the gene of modern science evolved, Creationism is slowly being killed off by this new a better gene of understanding the universe. One of Creationism's last gasp attempts at survival is the modern ID gene mutation. This mutation evolved in a myth hostile environment and it too will soon become extinct.
Selection doesn't look for anything. It simply disgards bad tosses. In non-sexual organisms, fatal mutations are inconsequential because the rate of reproduction ensures plenty of good copies. In sexual reproduction, most fatal mutations are weeded out before conception.
Most mutations are neutral or non-fatal.
Your statement about genes "not working yet" implies that a stairway doesn't exist if it doesn't reach the landing. But it is possible for neutral or garbage DNA to contain partial stairways that suddenly become significant when the last board becomes available.
The existence of junk DNA is proof that previous tosses are not thrown out. Much of what is currently non-functional was probably functional in a previous context.