I keep track of feedings, weights, sheds and when I clean their viv. I also make note of their DOB and when I acquired them. I keep it all in an excel sheet. Looks something like this.

Mouse
DOB:~ Aug 05
Date aquired:2/20/2006
Morph:normal
Gender:male

ActivityDate
Ate 20-Feb (fuzzy/hopper) = 1
Shed
clean viv

Works for me!