Overview: I have several related inventions in a slowly emerging industry.
Goal of minimizing upfront cost: I'm trying to preserve an early priority date while minimizing/delaying upfront cost as long as possible. Later (in a year or two) I will care less about cost and more about growing the portfolio.
Proposed action: Therefore the strategy is to file one comprehensive PCT application this summer (based on several provisionals from past months), pursue this single PCT application into the national phases; and later derive several divisionals from it with separate sets of claims, each covering one specific application of the invention (which are all covered by the original specifications).
Question: When is the latest time for a PCT application to branch out into divisionals? How far into the PCT national phase? Are there different factors to be considered for different countries (I care about US, Europe, Canada, Japan, China)?
PS: Why even have the divisionals? Technically, the scope of the invention could be covered by the one large PCT application with a long list of claims -- but the rationale for branching out later is that a larger portfolio with multiple granted patents will be harder to attack and look more valuable to potential buyers/investors.