My midwife suggested this : Pick a day, and a time. Write the time on a calender. Stare at it for a few minutes. Then say to yourself 21 times (apparently a magical habit forming nubmer) I'm going into labour on (date) at (time). Repeat every time you get fed up or at least twice a day.

I did do it (I chose 30th November at 7am), but then got fed up with the whole pregnancy pain thing and demanded an induction anyway.

Raspberry leaf tablets are still an option. They're stronger than the tea but still totally safe.