Question on Small Eggs Verse Large eggs

[Ole Mule]

I have a question. I hatched one egg early like two days early, and am still waiting on four other eggs to pip and hatch. The egg that hatched early was smaller and from smaller hens. The four I am waiting on are Welsummer Eggs. Do light weight breeds hatch earlier than heavy weight birds and does smaller eggs hatch earlier than larger eggs?

 

[Southernbelle]

Generally, they all hatch right around 21 days. I know one exception are Seramas - they're very small bantams and they typically hatch in 19 days.