When my EQ FICO was 780 or so, using a card that had been unused for awhile seemed to hit me for 3-6 points. Now with a 701, it doesn't change at all. I normally run into this when using my Kohl's charge, which sometimes goes unused for months at a time. Based upon my experience when I had high 700s, I learned to just pay before statment date. One month I forgot and it didn't change my score at all (EQ FICO). Now I don't worry about it any longer.
If the one additional charge gets you to the point where you have "too many accounts with balances", then expect more point loss.
Edited to type my response in after my cat decided to hit <Enter> for me giving me a blank reply.
