Retrieve con vars in InitPostEntity hook


I am trying to retrieve con vars in the InitPostEntity hook, but it seems that the content of the evaluated server.cfg isn’t reachable there.
I have tried to use GetConVar(String).

I created the convar like the following:

CreateConVar("ds_rounds", 0, bit.bor(0), "How many rounds" )

Accessing hostname delivers the “old” servername instead of the configured in the server.cfg.

Do I need a later hook or did I missed anything?