The first time, though of course he doesn't know it's the first time, everything went exactly according to plan. Crowley got the baby, right on time. He took it to the nunnery, and didn't stop to talk to the man waiting outside. He observed the whole thing, and made sure no funny business happened. At the end of the night, the Antichrist went home with the Dowlings.
It takes 600 more tries to get it going exactly according to the right plan.
When Primo returns from Rome the boy is dead. It doesn't last.
Unpleasant things happen to Jim Halsey, several times in a row but not in any particular order.
An operative from the future tells Wade that he has two options: kill himself before he has a chance to live 2000 years and become Cable's accomplice in dictatorship, or kill Cable. So now, Wade has thirty days to figure out a way to die. Unfortunately, most of his ideas involve convincing Cable to kill him. Fortunately, most of Cable's ideas for stopping him involve sex.