One can say that, in a large manufacture, the minimum reasonable time beetween an idea (a concept) and the presentation of an industrialized watch (ready to be produced) is 18 months ; But this can increase up to 4-5 years if the watch is complicated. Moreover, this is valid provided you have the necessary ressources in terms of talents as well as in terms of money.
It is true to say that we, as a small and independant manufacture, have limited ressources (specially money) and this makes our developpment times to increase : As an example, the development time for the Goldpfeil was 2 years, but the first Trio was presented in 2001 and we are only now (end of 2005 !) about to unveil the watch as it is to be delivered to customers.