It is much easier to hold one then to push one, most of the calves at our county fair, which falls the first week of July, need to be born early in the year. It can be real tough to get a late March early April calf to reach its potential, Like stated above it is a matter of managing them so the hit 12 o'clock at the right time. 18 months is not really that old, besides some genetics need the extra time anyway.