Hello Pheno,
Ah, I was right...damn, my memory isn't too bad after all. There is something about that breed of dog I have always liked...great little family you have there.
I understand your worry in terms of where you are in flower and the time left to maturity. I again can only speak to what I know, and this doesn't necessarily correlate to your situation, largely because every plant is different, but in terms of the AI, from what I've seen they'll go a solid 9-11 weeks and this is from the change in photoperiod...with 11 being the perceived norm in my book. With that being said, unless you've got plenty of nutrients in your soil, you're going to need to go a little longer into your feeding. Use this as an opportunity to add some cal/mag or whatever you think may help out.
Here's a little food for thought...earthworm castings, simply put on the top layer of the soil and watered in, or a simple tea may give you the little boost you need without going over board, while addressing some of your 'slight' deficiencies in the process.
Let me know what you determine / do with the 'rust' so I can put that information in my data base (aka brain) for future reference.
Enjoy the balance to your weekend!