Hey, I'm in the same school system as Wild Woman, and it is indeed a huge help to have (1) a daily planner book and (2) an online system where teachers post assignments. You need to get on top of whether your GD has a planner (if the school does not assign one you need to make one and check it with her every single day. Let me say it again: Every. Single. Day. Consistently. Including Friday after school for weekend homework!
She must, must write every assignment down. If the school does not assign her a planner and you make your own, you may need to talk with her main teacher about looking at the planner daily (for a while, not forever) to see that she is writing things down, but you also must make it the priority to sit down and say, "OK, what is on your planner for tonight" AND "What is due tomorrow, the next day, Friday, next Monday" and so on. Long-term thinking!
Blackboard and other online systems are great but only if teachers actually do post everything that's assigned. If not, you need to learn which teachers use the system consistently and which just don't, so you can remember to check in: "Sally, you know that Mrs. X doesn't tend to post assignments on Blackboard, so it's extra important to have her assignments in your own book."
Get her a good, big calendar with large boxes for each day, one that shows the whole month on a single page, and have her create her own deadlines for longer-term things so she can SEE them. Put it somewhere prominent and be sure that she knows you check it too, every day.
Sally needs to be increasingly responsible for knowing what she has due, but for a time, it is perfectly OK (and not being a "helicopter parent"!) for you to help her LEARN to be organized and think long-term. It really is OK, because kids have to be taught to get themselves organized for school - they don't come out of the womb knowing that "If I have something due for history two weeks from today, I can do parts 1 and 2 of it by Monday and then part 3 next week but only after the math test is over with on Wednesday..." Some parents insist that kids must sink or swim, take the consequences, learn from mistakes, etc. and that's true-- to a degree. But kids are just not able to teach themselves organization and it's fine to help her see why it does not work to wait until the last minute to do things. Forget the grade aspect -- the stress alone is horrid if she makes waiting into a habit.
To answer the specific questions -- I would not wait to say something to her; I would not give a consequence for not telling you but would be clear that the consequence is going to be a bad grade and she needs to get to work, now. Did you tell hear earlier, very clearly, "If you do not tell me about an assignment the very same day it is assigned, you will have a consequence?" If not -- why should she get one?
I think you are perhaps overly focused on consequences for not telling you, when the focus needs to shift instead to teaching her the steps she must take, every day, to be sure she has all assignments written down and to check those with you every single day. You will have to check in with her -- without nagging -- but reminding her that she must look not just at "what homework is due tomorrow" but at reducing longer-term projects etc. to tasks she spreads out over time.