How fast should I go up to castle age on maps like arabia where fast castling probably isnt an option?

Hi

I'm pretty new to online aoe2 and have read that fast castling isn't usually the best idea on maps like arabia where the opponent is likely to scout rush. What sort of time and villager count should I be aiming to get up to castle age for if I am going to make spears to counter a likely scout rush. Also any idea on defending a scout rush, I try to palisade wall and use my houses, barracks, mining camps etc to wall between tree lines and gold/stone but I usually get scout rushed before I can get the walls and stuff up. Thanks.