Gimme A Guideline!

I spent my entire Saturday teaching (forcing) my child to blow his own nose.  I know what you're thinking.  He's FIVE.  What 5 year-old can't blow his nose?  Well, when God passed out the love-of-all-things-grotesque quality to little boys, my son must have been busy cooking a mean risotto or admiring the daisies.  Because bodily functions repulse him.  (I know little boys who call their moms into the bathroom to look at what they did in the toilet because it's "awesome."  My kid?  Keeps his eyes on the ceiling and yells "Hurry up and flush it down!!")
So this morning, my son woke me at an obscene hour with a tissue in hand, saying, "I know it's still dark out and I'm not supposed to wake you yet, but... blow my nose."  It being a Saturday, and one of the only days that I can sleep past 7am, you will (hopefully) empathize with my response:  "Today is the day you will learn to blow your own nose.  And if you ever want to see the Super Mario Brothers again, you had better figure it out." (In hindsight, I probably should not have approached the situation like a kidnapper asking for ransom.)  Wouldn't you know, the kid blew his nose on the first try.
Moments like these would be easier if the parenting experts of the world set up some guidelines.  You know, like "Start baby on solid foods by 6 months."  "Take away the pacifier by age 1."  "Put them in a car seat until they get a license."  (At least that's what it seems like.  I mean, 4 foot 9?  Please.  I'm pretty sure my mother piled large suitcases around my infant body to keep me from rolling to the floor.  And my grandpa let me ride in the bed of his pickup truck at age 5 so that my ice cream didn't melt on the upholstery.)  How else am I to know the exact age that my kid should be blowing his own nose?
While we're at it, another guideline I would like some insight on is this:  At what age do I stop bathing my son, and make him take his own shower?  (Though let's be honest.  Even if there were a book with this information, would I read it?  Probably not.  It would cut into my Facebook time.)
After polling some Cool Moms, I decided to put my kiddo in the shower with my husband to make the transition easier.  Unfortunately, this was met with rather... unpleasant reactions from both parties.  Upon realizing which body parts were at eye level with my son's gaze, my husband demanded a pair of swim trunks.  And now my son showers with his eyes closed.
If there is, in fact, a manual for these types of scenarios, feel free to point me in the right direction.  Though you should probably post it as your Status Update, or put it on Twitter.  My attention bottoms out at 140 characters.