I know that one should not wash his clothes during the 9 days, and that one should also not wear "freshly laundered clothes" during this time except on Shabbos. My question is, what constitutes "freshly laundered clothes"? Is it permissible to do laundry immediately before the 9 days and then wear those clothes during the 9 days? Thanks all for your help.
It seems you are asking if "freshly laundered" means not worn since the last time they were laundered or if it means that they just came out of the laundry recently (time-wise). Obviously, the phrase "freshly laundered" doesn't show up in the Shulchan Aruch, but looking at what he does say (OC 551:3):
וכן המכובסים מקודם, בין ללבוש בין להציע בהם המטה
And similarly [included in the prohibition is] that which was laundered before [the Nine Days], whether to wear it or to spread it on a bed [ie a sheet].
He doesn't mention any time factor, but just seems to include anything that had previously been laundered (and presumably not worn). This is the common practice among everyone I know.
Per Orach Chaim 551:3 freshly laundered clothing and linen such as towels, sheets and tablecloths, may not be worn or used during the Nine Days.