HG. p8 said:
CONSTRUCTION TIMES
Construction times vary wildly, depending on the size and complexity of the spacecraft and the capabilities of the shipyard. On average, assume that it takes one day per million credits to build a spacecraft at an average commercial shipyard.
This tells us absolutely nothing about how long it takes to build a Tigress at a Naval Depot. This tells us something about how long it takes to build a Free Trader at your local small-business-friendly yard.
Remember, the Imperial Navy has thousands of capital ships, and probably buys/builds them in lots of tens or hundreds. The scale is completely different from modern capital ship construction.
Other editions hints that it takes in the order of a few years to build even the biggest ships, and that process can be speeded up considerably with experience and throwing resources at it.