Let's start off with CHRONO events. For some it's a pure power push event so dont apply as much to them. For those others it's a time struggle. If it's a 3 day CHRONO event, day one points only rack up once every hour. Day 2 points rack up 2 times per hour. Day 3 topping both days matters the most to pay attention to as it gives points 4x per hour. The position that you end in has nothing to do with where you place at, the points racked in over the whole event determine placements. So if you enter early gain what points you can with limited experience till the last day and a half when you need to pay attention and keep checking in to keep up on points to place top 15...
Regular events it doesn't matter when you enter just pay attention when it comes down to the end. I still try to keep up on them because at times you can see people you can beat but cant get through the wall of toons to get to them. All depends on how you want to play, limited experience, mid experience, or all out brawl for it all.