First egg!!!

My oldest hen finally laid her first egg today! So exciting!! She starting squatting when I approached her within the last week and has been laying in the nest box the last three mornings and today was the first time she laid an egg! I was a little skeptical she might have been a rooster she has a large comb and wattles and is very vocal sometimes my neighbors can hear her squawking in the morning when she wants some food. I have a couple questions, I have three other hens, one is almost the same age and should be laying very soon and the other two are a few months younger. They are all still on grower feed how do I switch to layer when only one hen out of four is laying? Also do you guys refrigerate your eggs or leave them on the counter?? Thanks so much!!! Wahoo