Of course there are a lot of variables involved in my opinion. I mean different lines and varieties tend to take different times to grow and finish. Some lines and varieties mature a little earlier. From my experience your solid color varieties tend to finish faster than multicolored birds. Most bantams though I would try and plan them to be around 6 months old by show time. The real key I found is the closer to point of lay they are the better. So I recommend keeping track of your line and see how long it takes for them to reach the point of lay and then plan accordingly for any shows you may attend.