It's four weeks today since I put 16 mats in place (two on my power panel, and 14 in my system). Wow! Basically, the longer I leave them in place, undisturbed, the more real, solid, immediate, involving and natural sounding the music (and the space it is being performed in) gets.
If your experience is like mine, you will hear improvements in transparency and detail immediately, or fairly soon after, placing them. During the first two weeks the sound will vary from day to day, with it being “off” some days (usually followed by being really “on” the next day). Around two weeks, there will be a “pop” in the the sound quality. It will then continue to improve consistently out to three weeks, then four...and beyond?