The hossy told me to have it done by about 34 weeks. With DS1 I did it at 38 weeks, and to me it was a mental milestone - it was a sign that I was "ready" to have the baby. With DS2 I was going to do it as soon as my maternity leave started (36 weeks). But he arrived the day before my maternity leave started. And the labour was 3 hours so no time to do it before racing off to hossy either! So in fact it never got done! Luckily I had bought the maternity pads and breast pads already, so I grabbed those and a change of clothes and toothbrush while DH was putting DS1 in the car, and DH brought me the rest of what I needed the next day.