You should really pre-soak the Vanilla beans for a week (or 2) in 4 (or 8) oz of cheap Vodka or 120 or 151 proof Everclear in a lidded half pint (or pint) mason jar. Room temps are fine. Shake whenever you get a chance.
Do a search on how to do this best, there are a few approaches to get the most from the vanilla beans. Slicing and scraping, chopping the rest. Also quick low heat extractions.
The other ingredients, add directly to your fermenter when fermentation is slowing down or 5 days before packaging.
At bottling/kegging time, strain the vanilla bean potion and add directly to the bottling bucket or inject into the keg. That way you waste nothing of the precious and expensive vanilla.
I've soaked slightly toasted cocoa nibs in alcohol, they fall apart after a week or so, and it becomes a thick paste. I've thinned down the paste and added it to the fermenter a few days before packaging, with a gentle stir once or twice a day, under CO2.
My fermenter buckets remain closed, I have a stoppered 1" access hole in the lid for adding things and stirring while streaming CO2 in through the airlock hole. This is to reduce or prevent air from getting inside causing oxidation. The lids seal well, I can build up pressure.
