<p>Most people struggle with 18 or 19 in their sophomore, junior and senior years. You really want to take a reasonable course load your very first semester; trying to do too much classes-wise while trying to get adjusted to college will burn you out.
On the other hand, you can always start out with a lot of classes and then just drop them if it becomes too much (you have 7 whole weeks to do this). It's generally much easier to drop classes than add them.</p>