<p>If you put a “tentative” major or school on your app, that’s what you’re classified under going in (you can always change it). Each semester that school mails you a checklist and the grad. requirements for your major so you know what you have and haven’t done. Or maybe just Natural Sciences does that, idk. And you can always schedule an appt with your major’s/school’s advisor throughout the year if you want.</p>
<p>For most people it’s about 2 or 3 classes a day, like 3 classes Monday, Wednesday, and Friday (MWF) and 2 classes on Tuesdays and Thursdays (TR). You usually have options in working out your schedule though (unless you register for lots of classes that only offer one section, etc.), so it’s also not uncommon to know someone who got themselves 4 classes on MWF and 1 class on TR or some similar combo and have massive chunks of “free” time - when they really should study but won’t. 
A few classes (like in visual arts) have longer Monday and Wednesday classes, and so they don’t have Friday class. I only have one morning class on Fridays next semester.</p>
<p>I recommend signing up for 18 to 20 credits, and then DROPPING one or two classes that you just don’t like or are too time-consuming. You don’t want to overwork yourself first semester - you spent all four yrs in high school doing that, now it’s time to relax a teeny bit 
It’s a good idea to try out a class or two during the free shopping period because why not? But do NOT be scared or too stubborn to drop something when you feel you’ve stretched yourself too thin. You’ll just wind up stressed, fat, and with low grades. :D</p>
<p>This might all sound complicated, but I assure you it’s not. And there is tons of help if you need it. Mainly enjoy your summer and don’t start stressing about this stuff yet (or ever) because you’ll figure it out during O-Week, like everyong else is saying.</p>