Most of your specs look pretty easy to meet. The one that may be the most challenging is early/fast flowering. Here's a link to a dioecious plant list:

Here is a link that might be useful: Dioecious Plants

I noticed in the UBC site where you were considering Amaranthus palmeri. Sounds like an interesting choice, and, since it's an annual, it will hopefully meet your fast flowering requirement. The research about how glyphosate resistance is being increasingly spread because of the dioecious nature of this species might also add interest.

it doesnt look like any of those plants on that list were fast growing...
does it have to be Dioecious?

The Amaranthus is a fast growing annual.

Thanks for your input, I think the Amaranth palmeri is probably the plant for me, how difficult would it be to obtain seeds and germination info?

I know it is considered a noxious weed in parts of the US due to its adverse effects on the soybean and corn crops,

However, in south and central America, it is a highly prized grain used to make a traditional candy...http://www.delange.org/Amaranth/Amaranth.htm

I'd post to the Seed Exchange Forum. I bet someone there might be able to help obtain seed. You might also check in the Farm Life Forum. I've never checked that forum out, but I'd imagine lots of farmers with Carelessweed/Palmer Amaranth/Pigweed problems there.

BTW, the correct scientific name is Amaranthus palmeri.

Germination should be a breeze. Amaranthus palmeri germinates quickly and at a high rate. Varying temperatures increase rates even further. Details are readily available online if you google 'Amaranthus palmeri germination'.