Hello,
on many places I met the statement that you cannot build units in the space dock which you build recent game round. Ok, but I cannot find any rule in the original rules or errata which states this ... by my opinion.
In the original rules is stated on p. 26 in section Building a new Space Dock that you must control planet for entire round. That's clear. Than I think more than a rule it is mentioned that: "Next round the Space Dock may begin producing units for its owner." This is clear since most of the time you are unable to deactivate the system where you produced the space dock. Or it is really the rule?!
In the section Building units at a Space Dock is required only the activation of the system.
(We played it the way that if you are able to deactivate the system (e.g. through Warfare SC) you can build in the system immediately. Me personaly like this cause it seems to me, that it provides wider range of tactical options than the 3 round to build rule. However, I would like to know the right rule.)