The best time to ask your boss for time off is when he is heading out the door. :)
The conversation with my boss went very well. He smilingly okayed a month off, saying that it was a great life event and I should celebrate and enjoy it. Then he said we should sit down and prioritize what needs to get done in the next 8 weeks and that I should really work hard on bringing at least one of my projects to some semblance of completion. I am going to be working my ass off for the next 8 weeks, and hopefully lose some weight too in the process, so that I can fit in my wedding sari with enough left for the pallu.