I guess I'm assuming that designs are finished, they are past the prototype stage and well into certifications.
Sounds like the manufacturing chain is done and perhaps priced and contracted.
This gets back to the age old question of how long is too long to announce new products.
You want to get the buzz going to stimulate sales ASAP but also not too soon to piss customers off by mentioning some new great thing and make them wait years for it.
You just never know how much tweaking will be needed. TrickFish as an example thought everything was good to go last year, as far as I have heard only cabs have shipped so far. Not their fault, just the way things are these days unless you want to be a small scale boutique builder with greatly limited production.