[Taqwus]

Early on, rapid expansion is far more important than leaving temples everywhere you go. That means putting money into troops, fast (well, unless you're AE Ermor) -- mercenaries, for instance. Even in SP.

400 gold will buy you a temple... or it might buy you a mage or two for research, or better yet, it'll cover most mercenary bands in SP which will let you capture more provinces faster for more income. Worry about more temples if your dominion is being stomped, or once you don't have as pressing a need for spending all your Au on troops and mages.