First of all, Glocks do, in fact, have a real safety.
They have three (3) internal safeties.
Second, as stated by Mr_Draco above, when seconds count....
If you are just carrying because you think it makes you cool, then no, do not chamber a round. Also, please reevaluate your life.
If you actually need a weapon, what is the point of needing it and not having it ready?