I almost forgot, from what I understand, a bull can grow about an inch a day, but you have to remember genetics are going to come into play big time, your not going to see a bull get an inch a day in flat out tine length, thats not the way it works, you will get mass and width and tine length. That all goes into account when figuring out what kindof bull your looking at.
I also think a bull will top out so to speak, he will reach a point where hes just not going to get much bigger, even in the in the Velvet or if it seems early or not, he may done even in the 3rd week of July, not saying that is always the case but I have seen bulls that it seemed like they just stopped growing alittle early. I dont know if lack of water,feed,genetics or what makes this happen. You should be able to tell now if the bull you are looking at is a good one or not.
Best of Luck on watching that BULL!