Dave yep I have seen that too when I wanted to register start of this month. Really strange, why artificially limit dates if you can get it out of the way in advance and keep a buffer if any issues come up.
I hope that means it's just a formality and you'll get an instant approval. E.g. as it is with the NZETA which also come through instantly.

I'll be able to submit our registration end of May, if there's no further responses here on that until then I can share my experience.