I purchased eggs from a gentleman in my town. So far I have 28 that are developing. Today is day number 17. I looked at my eggs this morning with a candle to make sure that progress was being made before I put them on lock down tomorrow. It seems that some of the eggs are so full you can barely see anything and others have a lot of space left. The man I purchased my eggs from assured me that they were all laid on the same day. Is it normal for some of the chicks to be much smaller than others?