Congratulations on successfully germinating them! I appreciate you sharing your notes with the community at large; if I may ask, which (if any) website did you get your cultivation/germination info from, or were you going off of past experience and blind experimentation? I'd love to know how many have sprouted/germinated so far (some state it can take 2-12 months for them to sprout), and how they're faring (as well as growing conditions, more pictures, germ rate ATM, etc.) for the time being alongside any other notes you may have on your quest to grow this terrific tea tree.
I do indeed support the idea that the fresher the seed, the better chance it'll have of germinating. When I harvested the yerba mate berries, I pulverized them in a pestle & mortar, put goop in strainer, ran tap water thru strainer to get gunk off, then threw a third in the oven around 100 centigrade for a few minutes, two thirds I wiped off with paper towels and let dry on my counter before half of those got refrigerated for a few days (before sending), the others merely sitting on my kitchen counter for a few days. I sent equal portions of all groups of seeds to you along with everybody else who participated in the giveaway (unfortunately my lazy touchis forgot to label which seeds had what treatment applied to them before sending... oh well... at least they were dry when bagged and shipped.)
I would like to hear back from the others to whom I sent mate seeds to as well. Germinating mate is quite a challenge, and i'd love to see how everyone else is progressing with respect to germinating their seeds.
Mazel Tov,
-Mangrove