I planned to go at 36 weeks but went at 34 because I was wiped out but next time I would go way way earlier. Maybe 30 weeks, my employer is quite flexible about when you start your twelve months leave. I found the last four weeks I was uncomfortable and not reallly working at my best. When my little boy was 10 months I was pretty keen to go back so I really could have gone on leave a fair bit earlier.

Talk to your HR and remember you can ask them to keep your enquiry confidential.