By looking at my autograph on any card you can tell what time period the card was signed (except for the numbers 72 & 17 which I am right now and have been in the past.)

If you look at the end of the autograph there will be a number

41 = July 2002 - May 2003
27 = May 10th 2003 - June 15th 2003
16 = June 16th 2003 - August 14th 2003 (Pretty Rare)
36 = August 15th 2003 - September 28th 2003 (Also Rare)
49 = September 29th 2003 - April 8th 2004
17 = April 9th 2004 - July 16th 2004
27 with a dot by the 7 = July 16th 2004 - July 18th 2004
26 = July 19th 2004 - April 6th 2005
28 = April 7th 2005 - February 19th 2006
72 = February 20th 2006 - April 5th 2006
47 = April 6th - July 6th 2006
72 = July 7th - July 12th 2006 (Short period of switching numbers)
17 = July 7th 2006 - Present

I never knew Pat Neshek did this, kind of cool if you are buying his autograph. He does this with certified examples as well.