When it split in half, did it fall apart? :-)
If not, that is usually the first sign that it's gonna sprout!

It takes awhile...

Well the first time I tried it it did split in half and fell apart into 2
pieces, It fell apart after maybe 2 weeks, I tried to keep it in the water for
another 2 weeks but wasn't very successful, Everytime I turned around the
toothpicks had slipped or broke free and it always sank to the bottom of the
glass totally underwater. There was no sprouting, not even any sign of
sprouting so after a month or so I finally gave up and tossed it. But it broke
right down the center of the seed.
Steve