Well, remember that you can only send one submission at a time and you have to wait for your feedback before you can send off another.
I imagine the slush pile is fairly large and the editors in charge have other jobs as well.
Therefore, as you might expect, it could take a while for you to get a response.
You might have a lot of ideas you want to submit before March, but I imagine you'll only be provided the time to submit one, maybe two if you're very lucky. So, choose wisely.
From what I understand, we have two minute to pitch our idea, and then the next person gets their chance. And it's first come, first served.
So, the panel lasts for 50 minutes, and I would expect a large queue of people wanting to pitch, even if you could rejoin the queue at the back, as it were, they're unlikely to get to you again.
Unless I'm very much mistaken, and there are only a few people wanting to pitch, then you will simply get the opportunity to pitch one idea and that's it.
I guess I better hope that I've picked a good enough idea.