This is the unabridged version of my after haircut washing theory.  

 

I don't recommend washing your hair after you get a haircut.  There are two main reasons why I say this.  First, you should wash your hair before you get a cut so that it is clean and free of products.  Since you should wash your hair prior to your cut, washing it afterwards is redundant and pulls out more of your hair's natural oils that its trying to reproduce.  That's also why I don't recommend over-washing.  Second, by not washing your hair right after you get a cut, you allow your haircut and your new length wave pattern to set in.  This is especially true if you do not have a strong base wave pattern.  Even if you have a strong wave pattern, you will lose some defintion if you immediately wash your hair after a cut.  I recommend brushing off the loose hairs with a soft brush, adding a moisturizer or small amount of pomade, if desired, followed by brushing and putting on a durag or wave cap, if possible.  After a couple of days, your hair cut and its pattern should be set and then it should be okay to wash. Also, note that you should use warm to semi-hot water, but not scolding hot, to wash your hair.  The warm to semi-hot water opens your hair's pores and allows your hair follicles and attached strands to relax causing your waves to lay down better while shower brushing.  It's the same concept that spas use for opening up your face's pores when they place a warm towel on it.  After you finish shower brushing apply a small amount of cool water to your head to allow your pores to re-close.  Then apply a moisturizer or pomade, if needed, and continue brushing.