It all depends on the nature of the illness.  My son has been reduced to one with just an ear infection---when he was four years old---and sometimes when they are babies you really cannot second guess you just have to go with your gut as they cannot communicate their needs.  I have had my child be sick and need double to triple dosing even without a temperature being evident---he has just comlained of nausea and we have immediately doubled his hydrocortisone without a second thought.  He has been in hospital three times throughout his life and had to have IV fluids as a result of such.  I have never yet given a solu cortef shot though I would if I needed to.  I have just took him straight to the hospital and they allow us to take him onto the childrens ward and skip the A & E at times as they new him well on the childrens ward after the first and second hospital stays.  I don't know if you have ever had a serious injury or suffered shock.  It happens pdq and I always imagine that at times like that that the pituitary gland is going to demand masses of cortisol immediately in response to such.  However with CAH  as you can imagine there is no production and I  always assume that  at a time like that, that Adrenal Crisis would happen within minutes.  maybe this is not the case, but sometimes there are these big demands made of the adrenal gland within what would seem like minutes and then with illness I imagine it to be sort of a slower build up as the illness becomes progressively worse.  Fortunately, I have never had my son be injured to be able to advise anyone if this is correct.  I don't think I would want to either.  Because a fever isn't iminent often until it peaks, you don't sometimes know what is coming and so your child is only hitting crisis point I notice at the last minute when you can't seem to keep the meds down.  With a broken arm I imagined it to be very much faster than all that as they tell you to move fast and give the shot immediately and the way it is written about in medical books I think I have assumed that.

JH