All I can do is echo the answer here. If you need something done in a timely manner, always phone/speak face to face and never email. People tend to ignore emails/forget about them.
Likewise she may not be aware of the date, so I'm sure with some gentle reminding she'll be more than happy to comply.
Incidentally, I sometimes find it helpful if a person seems a little unreliable to specify the date is a day or two early, so that when they miss it, panic and fill it in late, you're still on time.