I don't know if know, or ever, is the right time, to buy a brand new Patek - IF - you are buying because from an investment point of view you think there is an upside. There may be a few exceptions which might prove the rule, but those are limited to very limited (unique?) pieces. And what is becoming readily apparent as more supposedly "unique" watches reach the market, is that there are very, very few truly few unique pieces.
Having said that, there is every reason to buy the watch now if you are still are in love with it. It sounds like it will be an excellent investment in your happiness and the price for a BNIB one IMHO is unlikely to fall further.
I strongly believe that in buying a new Patek, you can be pretty sure if you want to get out of it, it won't be a disaster (unlike some other trendy brands) and in the mean time you will have bought for the right and purist (pun intended) of reasons, love of the watch and the intense joy of owning and wearing such an exceptional watch.
Who knows, maybe it will be like the 5020, which was far from popular, few pieces were sold and now is considered a "grail" watch, both among vintage and modern collectors. But don't count on it and consider it an unexpected bonus if that happens.
Best,
patekova