Okay, thinking through from the beginning, my first idea is as follows:
Set-up Phase
Teams form lines in the first minute.
>One of the strengths of cavalry is to break up a formation, so if the cavalry is permitted to attack in the first 30 seconds, it will defeat the purpose of formation battles. Therefore, if there is a period at the beginning of the match (Set-up phase) for the teams to form their lines, units will be able to form (phalanx, light cavalry, heavy infantry, etc.), such that cavalry, as well as all other types of units, can be utilized to their full potential on the battlefield. The Set-up Phase should be between 30 seconds and 1:30, to allow teams to spawn and units to form. Remember, time is ticking for the battle, so lines must be formed quickly, so as not to delay. I propose after one minute in, cry havoc and let slip the dogs of war!