Rather be mocked for being optimistic in the face of people who don't seem to understand that construction companies do make allowances for potential problems with time frames than for being a bloody miserable bugger and press the panic button way too early...
We saw how quickly Fuji-Q's went up (2/3 weeks no?)... Let's panic in Feb if it's not been built yet eh? A month for building, a month for testing (whilst all the other odd jobs like paving, electricals, etc happen)... Groundwork takes the longest, and considering the weather, it's not a shock that it might well be behind schedule (which is just people guessing really, no enthusiast will be 100% privy to such data), but until I have hard evidence to support that it will not open on opening day, then I will be optimistic in my belief that the construction engineers will get it done...
Indeed, I'm sure if Towers get really worried, they'll tell the workers to increase productivity... I don't think that enthusiasts proclaiming it will not be built on time (whether it be serious or a 'laugh') is tantamount to a fun place... Especially when I doubt they might not have much knowledge about construction project techniques...
Tl;dr - Pessimistic enthusiasts should have a reason, like a crap plonked down ride being built so some stop gap cheap hotel in order to garner some extra income with minimal outlay... Jesus it's DIC all over again!