Depends on the stadium. Some (like Sloan Park/Cubs Complex) are a nightmare due to huge crowds every game. Others like Goodyear(Reds/Guardians) and Surprise(Royals/Rangers) are much more subdued.
As a general rule, if its your first time out, I would plan to arrive 1.5 hrs before the game if you want to park close. Get parked, take your time walking in, explore the ballpark prior to first pitch etc.