Is it OK that I didn't use hibiclens a full 3 days before breast augmentation?

Using hibiclens prior to surgery is a nice option to try and reduce the risk of a post-operative infection.  Most doctors don't have this requirement and the risk of infection is somewhere around 1-2%.  Using hibiclens prior to surgery may or may not actually reduce the infection rate, but it couldn't hurt (unless you have an allergy).  So, starting 2 days prior as opposed to 3 day will likely have no clinically appreciable difference.  The only case that it may be more important is if you have a known history of infections with a bacteria know as staph aureus.

Using Hibiclens before surgery is a great way to decrease the amount of bacteria  that naturally resides on your skin.   The fact that you used it for two days instead of three days should not matter at all. Many surgeons don't even routinely recommend it prior to surgery. Your skin will be meticulously prepped prior to the procedure. Most surgeons also use antibiotic solutions to irrigate the pockets before implant placement. You will also have IV antibiotics. You are fine!  Best wishes to you!