Considering the last figure (Elite Guard Optimus) was pushed back a month or two (and a few general release items in the last year)... I don't have much faith in TT to ever be early with a release.
If they already have the toy colours done and a sample produced, and the book is now out for pre-ordering, it suggests that it is ready to be produced right now but the publisher wants to make sure they produce enough to meet demand/orders. I guess with production/shipping-to-Japan times would account for the 4 months between pre-order cutoff and its release to customers. Maybe the 4 months of pre-orders is too long, making the 8 month wait longer than it should be.