I keep a garden journal of things that are happening in my yard: what's blooming/producing, weather, etc. This includes the egg count.
1st egg on Thanksgiving morning 2008
Nov 2008 = 3 (1 bird laying)
Dec 2008 = 32 (1 bird laying until 12/27, then 3)
Jan 2009 = 58 (3 birds laying for 2 weeks...