That's a cool idea but has one fatal flaw. What if you request a ship for immediate use -- like in defense of the planet where the Temporal Space Yard is located -- and
lose the battle. If the TSY is destroyed by orbital bombardment on the same or next turn after completing the ship, is it possible for the ship to have been completed in the 'future' after the battle?
I think the 'time slip' device to give a certain fixed percentage chance of being 'elsewhen' and avoiding weapon hits that would otherwise have occured is a better use of the temporal concept. (A flat chance for weapons to miss even if they get their 'to hit' percentage.) Also, some sort of 'time slowing' device for bogging down or completely stopping your enemy (think 'stasis device' from MOO) would also be nice. With actual tracking of supplies in SE we could give the device a very high supply usage, too, and set a practical limit to its use. Anyway, both devices are contained in the combat context and don't create strategic problems because of conflict between game events and the operation of the device(s).