[Edward Tinker]

That can be an indication, because they made serial numbers in certain "groupings", so some years didn't have, say an 'h". The 1920, usually isn't a year, but a Rheichswehr property stamp. 1920 guns are in the Weimar era when vast quanities of WW1 guns were refinished from older guns and many were also made.

In what is considered the "Alphabet" Lugers, made in the 20's and given serial numbers, there were no "h"s made, they started in the "i" block.

So, yours was made some time during the WW1 era and then used during the Weimar era. Good indications, but not proof positive are Weimar acceptance markings, and Imperial (WW1) markings, but many times these were scrubbed off.