I have four girls - two EEs, a Barred Rock and a Gold Laced Wyandotte. Laya, our all white EE, laid the first egg 2 days ago. She literally JUST laid her second 5 minutes ago. Her first was pretty small and a paler color than the second. The second is a tiiiiiiiiny bit bigger and quite a bit darker with pretty little white freckles. I'm wondering how soon I can expect the timing, size and color to be consistent.
With ducks and chickens alike, it takes a bit of time. It varies depending on the duck or chicken. When my duck started laying she was consistent almost right away. Just give her a bit of time.
My first layer has taken almost a month before laying consistent and larger eggs. Lots of weird ones initially. They are new to this so just be patient and give them time to sort it out.