Our First Egg

I am new to raising chickens. I have 6 Rhode Island Reds and one has starting laying at 18 weeks and in the nesting box! I let them out at around 11am to free range all day I was a hoping I was not going to have to egg hunt in the yard, so I feel lucky she knew where to lay as I have read hens can lay where ever. My other 5 haven't yet layed and its been 2 weeks since the first egg was layed from our 1 hen and she is now laying every day. When do you think the others will follow suite? I am hoping they are getting the idea of what to do and where to lay their egg from my girl that is laying.