when i noticed Madelines discharge she was already in labour she gave birth to her first kitten within two hours of the discharge.
I did not notice anything before this time although she did kinda smell funny from her rear end for about 5 days before giving birth. She had her kittens on day 64.
Each cat is different and if your cat is having discharge now i should imagine that birth will not be too far away. Its just a matter of sit and wait and when i was waiting for Madeline to have her babies i was more on edge than she was. I seemed to be waiting forever !!!
Good luck with everything and hopefully you shouldn't have to wait for too long !!!