Giner; I'm a transplant from MA and live in sunny FL. A few year back I went to the Keys where coconuts are all over the place. I picked up a fallen branch and took them back home. I did all sorts of research and was ready to germinate my own, although I could buy one at Home Depot for under $10. what I determined was "just eat the coconut" and buy one already started.
Here's what I found out: They take anywhere frm 6 months to a year to germinate if your lucky. You strip off the outer husk and plant them with the eyes up "the 3 or 4 indents at one end. Plant them with the eyes just above the soil. They need the heat and plenty of water. The plant lives on the coconut juice inside "Remember its pritty warm down here in the summer" So I planted several outside in the soil and some in pots. I did everything correct as far as I could tell "not one sprouted" All I can say is good luck. "I should have eaten them"
PS You might try soaking them in saltwater brine for a week or so first. I can grow just about anything "almost" They sell them already started so there must be something they do that I overlooked or was omitted in everything I read.